1219 lines
48 KiB
Java
1219 lines
48 KiB
Java
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/*
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* Copyright (c) 1994, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang;
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import java.lang.invoke.MethodHandles;
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import java.lang.constant.Constable;
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import java.lang.constant.ConstantDesc;
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import java.util.Optional;
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import jdk.internal.math.FloatingDecimal;
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import jdk.internal.math.DoubleConsts;
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import jdk.internal.vm.annotation.IntrinsicCandidate;
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/**
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* The {@code Double} class wraps a value of the primitive type
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* {@code double} in an object. An object of type
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* {@code Double} contains a single field whose type is
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* {@code double}.
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*
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* <p>In addition, this class provides several methods for converting a
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* {@code double} to a {@code String} and a
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* {@code String} to a {@code double}, as well as other
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* constants and methods useful when dealing with a
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* {@code double}.
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*
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* <!-- Android-removed: paragraph on ValueBased
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* <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
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* class; programmers should treat instances that are
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* {@linkplain #equals(Object) equal} as interchangeable and should not
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* use instances for synchronization, or unpredictable behavior may
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* occur. For example, in a future release, synchronization may fail.
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* -->
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*
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* <h2><a id=equivalenceRelation>Floating-point Equality, Equivalence,
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* and Comparison</a></h2>
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*
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* IEEE 754 floating-point values include finite nonzero values,
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* signed zeros ({@code +0.0} and {@code -0.0}), signed infinities
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* {@linkplain Double#POSITIVE_INFINITY positive infinity} and
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* {@linkplain Double#NEGATIVE_INFINITY negative infinity}), and
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* {@linkplain Double#NaN NaN} (not-a-number).
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*
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* <p>An <em>equivalence relation</em> on a set of values is a boolean
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* relation on pairs of values that is reflexive, symmetric, and
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* transitive. For more discussion of equivalence relations and object
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* equality, see the {@link Object#equals Object.equals}
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* specification. An equivalence relation partitions the values it
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* operates over into sets called <i>equivalence classes</i>. All the
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* members of the equivalence class are equal to each other under the
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* relation. An equivalence class may contain only a single member. At
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* least for some purposes, all the members of an equivalence class
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* are substitutable for each other. In particular, in a numeric
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* expression equivalent values can be <em>substituted</em> for one
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* another without changing the result of the expression, meaning
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* changing the equivalence class of the result of the expression.
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*
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* <p>Notably, the built-in {@code ==} operation on floating-point
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* values is <em>not</em> an equivalence relation. Despite not
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* defining an equivalence relation, the semantics of the IEEE 754
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* {@code ==} operator were deliberately designed to meet other needs
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* of numerical computation. There are two exceptions where the
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* properties of an equivalence relation are not satisfied by {@code
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* ==} on floating-point values:
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*
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* <ul>
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*
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* <li>If {@code v1} and {@code v2} are both NaN, then {@code v1
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* == v2} has the value {@code false}. Therefore, for two NaN
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* arguments the <em>reflexive</em> property of an equivalence
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* relation is <em>not</em> satisfied by the {@code ==} operator.
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*
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* <li>If {@code v1} represents {@code +0.0} while {@code v2}
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* represents {@code -0.0}, or vice versa, then {@code v1 == v2} has
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* the value {@code true} even though {@code +0.0} and {@code -0.0}
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* are distinguishable under various floating-point operations. For
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* example, {@code 1.0/+0.0} evaluates to positive infinity while
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* {@code 1.0/-0.0} evaluates to <em>negative</em> infinity and
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* positive infinity and negative infinity are neither equal to each
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* other nor equivalent to each other. Thus, while a signed zero input
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* most commonly determines the sign of a zero result, because of
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* dividing by zero, {@code +0.0} and {@code -0.0} may not be
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* substituted for each other in general. The sign of a zero input
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* also has a non-substitutable effect on the result of some math
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* library methods.
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*
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* </ul>
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*
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* <p>For ordered comparisons using the built-in comparison operators
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* ({@code <}, {@code <=}, etc.), NaN values have another anomalous
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* situation: a NaN is neither less than, nor greater than, nor equal
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* to any value, including itself. This means the <i>trichotomy of
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* comparison</i> does <em>not</em> hold.
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*
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* <p>To provide the appropriate semantics for {@code equals} and
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* {@code compareTo} methods, those methods cannot simply be wrappers
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* around {@code ==} or ordered comparison operations. Instead, {@link
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* Double#equals equals} defines NaN arguments to be equal to each
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* other and defines {@code +0.0} to <em>not</em> be equal to {@code
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* -0.0}, restoring reflexivity. For comparisons, {@link
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* Double#compareTo compareTo} defines a total order where {@code
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* -0.0} is less than {@code +0.0} and where a NaN is equal to itself
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* and considered greater than positive infinity.
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*
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* <p>The operational semantics of {@code equals} and {@code
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* compareTo} are expressed in terms of {@linkplain #doubleToLongBits
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* bit-wise converting} the floating-point values to integral values.
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*
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* <p>The <em>natural ordering</em> implemented by {@link #compareTo
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* compareTo} is {@linkplain Comparable consistent with equals}. That
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* is, two objects are reported as equal by {@code equals} if and only
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* if {@code compareTo} on those objects returns zero.
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*
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* <p>The adjusted behaviors defined for {@code equals} and {@code
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* compareTo} allow instances of wrapper classes to work properly with
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* conventional data structures. For example, defining NaN
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* values to be {@code equals} to one another allows NaN to be used as
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* an element of a {@link java.util.HashSet HashSet} or as the key of
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* a {@link java.util.HashMap HashMap}. Similarly, defining {@code
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* compareTo} as a total ordering, including {@code +0.0}, {@code
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* -0.0}, and NaN, allows instances of wrapper classes to be used as
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* elements of a {@link java.util.SortedSet SortedSet} or as keys of a
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* {@link java.util.SortedMap SortedMap}.
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*
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* @jls 4.2.3 Floating-Point Types, Formats, and Values
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* @jls 4.2.4. Floating-Point Operations
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* @jls 15.21.1 Numerical Equality Operators == and !=
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* @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
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*
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* @author Lee Boynton
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* @author Arthur van Hoff
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* @author Joseph D. Darcy
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* @since 1.0
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*/
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@jdk.internal.ValueBased
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public final class Double extends Number
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implements Comparable<Double>, Constable, ConstantDesc {
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/**
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* A constant holding the positive infinity of type
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* {@code double}. It is equal to the value returned by
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* {@code Double.longBitsToDouble(0x7ff0000000000000L)}.
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*/
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public static final double POSITIVE_INFINITY = 1.0 / 0.0;
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/**
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* A constant holding the negative infinity of type
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* {@code double}. It is equal to the value returned by
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* {@code Double.longBitsToDouble(0xfff0000000000000L)}.
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*/
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public static final double NEGATIVE_INFINITY = -1.0 / 0.0;
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/**
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* A constant holding a Not-a-Number (NaN) value of type
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* {@code double}. It is equivalent to the value returned by
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* {@code Double.longBitsToDouble(0x7ff8000000000000L)}.
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*/
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public static final double NaN = 0.0d / 0.0;
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/**
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* A constant holding the largest positive finite value of type
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* {@code double},
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* (2-2<sup>-52</sup>)·2<sup>1023</sup>. It is equal to
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* the hexadecimal floating-point literal
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* {@code 0x1.fffffffffffffP+1023} and also equal to
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* {@code Double.longBitsToDouble(0x7fefffffffffffffL)}.
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*/
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public static final double MAX_VALUE = 0x1.fffffffffffffP+1023; // 1.7976931348623157e+308
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/**
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* A constant holding the smallest positive normal value of type
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* {@code double}, 2<sup>-1022</sup>. It is equal to the
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* hexadecimal floating-point literal {@code 0x1.0p-1022} and also
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* equal to {@code Double.longBitsToDouble(0x0010000000000000L)}.
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*
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* @since 1.6
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*/
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public static final double MIN_NORMAL = 0x1.0p-1022; // 2.2250738585072014E-308
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/**
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* A constant holding the smallest positive nonzero value of type
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* {@code double}, 2<sup>-1074</sup>. It is equal to the
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* hexadecimal floating-point literal
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* {@code 0x0.0000000000001P-1022} and also equal to
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* {@code Double.longBitsToDouble(0x1L)}.
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*/
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public static final double MIN_VALUE = 0x0.0000000000001P-1022; // 4.9e-324
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/**
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* Maximum exponent a finite {@code double} variable may have.
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* It is equal to the value returned by
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* {@code Math.getExponent(Double.MAX_VALUE)}.
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*
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* @since 1.6
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*/
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public static final int MAX_EXPONENT = 1023;
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/**
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* Minimum exponent a normalized {@code double} variable may
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* have. It is equal to the value returned by
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* {@code Math.getExponent(Double.MIN_NORMAL)}.
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*
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* @since 1.6
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*/
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public static final int MIN_EXPONENT = -1022;
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/**
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* The number of bits used to represent a {@code double} value.
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*
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* @since 1.5
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*/
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public static final int SIZE = 64;
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/**
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* The number of bits in the significand of a {@code double} value.
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* This is the parameter N in section {@jls 4.2.3} of
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* <cite>The Java Language Specification</cite>.
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*
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* @since 19
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*/
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public static final int PRECISION = 53;
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/**
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* The number of bytes used to represent a {@code double} value.
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*
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* @since 1.8
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*/
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public static final int BYTES = SIZE / Byte.SIZE;
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/**
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* The {@code Class} instance representing the primitive type
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* {@code double}.
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*
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* @since 1.1
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*/
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@SuppressWarnings("unchecked")
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public static final Class<Double> TYPE = (Class<Double>) Class.getPrimitiveClass("double");
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/**
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* Returns a string representation of the {@code double}
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* argument. All characters mentioned below are ASCII characters.
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* <ul>
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* <li>If the argument is NaN, the result is the string
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* "{@code NaN}".
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* <li>Otherwise, the result is a string that represents the sign and
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* magnitude (absolute value) of the argument. If the sign is negative,
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* the first character of the result is '{@code -}'
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* ({@code '\u005Cu002D'}); if the sign is positive, no sign character
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* appears in the result. As for the magnitude <i>m</i>:
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* <ul>
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* <li>If <i>m</i> is infinity, it is represented by the characters
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* {@code "Infinity"}; thus, positive infinity produces the result
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* {@code "Infinity"} and negative infinity produces the result
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* {@code "-Infinity"}.
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*
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* <li>If <i>m</i> is zero, it is represented by the characters
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* {@code "0.0"}; thus, negative zero produces the result
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* {@code "-0.0"} and positive zero produces the result
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* {@code "0.0"}.
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*
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* <li>If <i>m</i> is greater than or equal to 10<sup>-3</sup> but less
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* than 10<sup>7</sup>, then it is represented as the integer part of
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* <i>m</i>, in decimal form with no leading zeroes, followed by
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* '{@code .}' ({@code '\u005Cu002E'}), followed by one or
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* more decimal digits representing the fractional part of <i>m</i>.
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*
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* <li>If <i>m</i> is less than 10<sup>-3</sup> or greater than or
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* equal to 10<sup>7</sup>, then it is represented in so-called
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* "computerized scientific notation." Let <i>n</i> be the unique
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* integer such that 10<sup><i>n</i></sup> ≤ <i>m</i> {@literal <}
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* 10<sup><i>n</i>+1</sup>; then let <i>a</i> be the
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* mathematically exact quotient of <i>m</i> and
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* 10<sup><i>n</i></sup> so that 1 ≤ <i>a</i> {@literal <} 10. The
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* magnitude is then represented as the integer part of <i>a</i>,
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* as a single decimal digit, followed by '{@code .}'
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* ({@code '\u005Cu002E'}), followed by decimal digits
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* representing the fractional part of <i>a</i>, followed by the
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* letter '{@code E}' ({@code '\u005Cu0045'}), followed
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* by a representation of <i>n</i> as a decimal integer, as
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* produced by the method {@link Integer#toString(int)}.
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* </ul>
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* </ul>
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||
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* How many digits must be printed for the fractional part of
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* <i>m</i> or <i>a</i>? There must be at least one digit to represent
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* the fractional part, and beyond that as many, but only as many, more
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* digits as are needed to uniquely distinguish the argument value from
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* adjacent values of type {@code double}. That is, suppose that
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* <i>x</i> is the exact mathematical value represented by the decimal
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* representation produced by this method for a finite nonzero argument
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* <i>d</i>. Then <i>d</i> must be the {@code double} value nearest
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* to <i>x</i>; or if two {@code double} values are equally close
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||
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* to <i>x</i>, then <i>d</i> must be one of them and the least
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||
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* significant bit of the significand of <i>d</i> must be {@code 0}.
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||
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*
|
||
|
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* <p>To create localized string representations of a floating-point
|
||
|
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* value, use subclasses of {@link java.text.NumberFormat}.
|
||
|
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*
|
||
|
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* @param d the {@code double} to be converted.
|
||
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* @return a string representation of the argument.
|
||
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*/
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public static String toString(double d) {
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return FloatingDecimal.toJavaFormatString(d);
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|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a hexadecimal string representation of the
|
||
|
|
* {@code double} argument. All characters mentioned below
|
||
|
|
* are ASCII characters.
|
||
|
|
*
|
||
|
|
* <ul>
|
||
|
|
* <li>If the argument is NaN, the result is the string
|
||
|
|
* "{@code NaN}".
|
||
|
|
* <li>Otherwise, the result is a string that represents the sign
|
||
|
|
* and magnitude of the argument. If the sign is negative, the
|
||
|
|
* first character of the result is '{@code -}'
|
||
|
|
* ({@code '\u005Cu002D'}); if the sign is positive, no sign
|
||
|
|
* character appears in the result. As for the magnitude <i>m</i>:
|
||
|
|
*
|
||
|
|
* <ul>
|
||
|
|
* <li>If <i>m</i> is infinity, it is represented by the string
|
||
|
|
* {@code "Infinity"}; thus, positive infinity produces the
|
||
|
|
* result {@code "Infinity"} and negative infinity produces
|
||
|
|
* the result {@code "-Infinity"}.
|
||
|
|
*
|
||
|
|
* <li>If <i>m</i> is zero, it is represented by the string
|
||
|
|
* {@code "0x0.0p0"}; thus, negative zero produces the result
|
||
|
|
* {@code "-0x0.0p0"} and positive zero produces the result
|
||
|
|
* {@code "0x0.0p0"}.
|
||
|
|
*
|
||
|
|
* <li>If <i>m</i> is a {@code double} value with a
|
||
|
|
* normalized representation, substrings are used to represent the
|
||
|
|
* significand and exponent fields. The significand is
|
||
|
|
* represented by the characters {@code "0x1."}
|
||
|
|
* followed by a lowercase hexadecimal representation of the rest
|
||
|
|
* of the significand as a fraction. Trailing zeros in the
|
||
|
|
* hexadecimal representation are removed unless all the digits
|
||
|
|
* are zero, in which case a single zero is used. Next, the
|
||
|
|
* exponent is represented by {@code "p"} followed
|
||
|
|
* by a decimal string of the unbiased exponent as if produced by
|
||
|
|
* a call to {@link Integer#toString(int) Integer.toString} on the
|
||
|
|
* exponent value.
|
||
|
|
*
|
||
|
|
* <li>If <i>m</i> is a {@code double} value with a subnormal
|
||
|
|
* representation, the significand is represented by the
|
||
|
|
* characters {@code "0x0."} followed by a
|
||
|
|
* hexadecimal representation of the rest of the significand as a
|
||
|
|
* fraction. Trailing zeros in the hexadecimal representation are
|
||
|
|
* removed. Next, the exponent is represented by
|
||
|
|
* {@code "p-1022"}. Note that there must be at
|
||
|
|
* least one nonzero digit in a subnormal significand.
|
||
|
|
*
|
||
|
|
* </ul>
|
||
|
|
*
|
||
|
|
* </ul>
|
||
|
|
*
|
||
|
|
* <table class="striped">
|
||
|
|
* <caption>Examples</caption>
|
||
|
|
* <thead>
|
||
|
|
* <tr><th scope="col">Floating-point Value</th><th scope="col">Hexadecimal String</th>
|
||
|
|
* </thead>
|
||
|
|
* <tbody style="text-align:right">
|
||
|
|
* <tr><th scope="row">{@code 1.0}</th> <td>{@code 0x1.0p0}</td>
|
||
|
|
* <tr><th scope="row">{@code -1.0}</th> <td>{@code -0x1.0p0}</td>
|
||
|
|
* <tr><th scope="row">{@code 2.0}</th> <td>{@code 0x1.0p1}</td>
|
||
|
|
* <tr><th scope="row">{@code 3.0}</th> <td>{@code 0x1.8p1}</td>
|
||
|
|
* <tr><th scope="row">{@code 0.5}</th> <td>{@code 0x1.0p-1}</td>
|
||
|
|
* <tr><th scope="row">{@code 0.25}</th> <td>{@code 0x1.0p-2}</td>
|
||
|
|
* <tr><th scope="row">{@code Double.MAX_VALUE}</th>
|
||
|
|
* <td>{@code 0x1.fffffffffffffp1023}</td>
|
||
|
|
* <tr><th scope="row">{@code Minimum Normal Value}</th>
|
||
|
|
* <td>{@code 0x1.0p-1022}</td>
|
||
|
|
* <tr><th scope="row">{@code Maximum Subnormal Value}</th>
|
||
|
|
* <td>{@code 0x0.fffffffffffffp-1022}</td>
|
||
|
|
* <tr><th scope="row">{@code Double.MIN_VALUE}</th>
|
||
|
|
* <td>{@code 0x0.0000000000001p-1022}</td>
|
||
|
|
* </tbody>
|
||
|
|
* </table>
|
||
|
|
* @param d the {@code double} to be converted.
|
||
|
|
* @return a hex string representation of the argument.
|
||
|
|
* @since 1.5
|
||
|
|
* @author Joseph D. Darcy
|
||
|
|
*/
|
||
|
|
public static String toHexString(double d) {
|
||
|
|
/*
|
||
|
|
* Modeled after the "a" conversion specifier in C99, section
|
||
|
|
* 7.19.6.1; however, the output of this method is more
|
||
|
|
* tightly specified.
|
||
|
|
*/
|
||
|
|
if (!isFinite(d) )
|
||
|
|
// For infinity and NaN, use the decimal output.
|
||
|
|
return Double.toString(d);
|
||
|
|
else {
|
||
|
|
// Initialized to maximum size of output.
|
||
|
|
StringBuilder answer = new StringBuilder(24);
|
||
|
|
|
||
|
|
if (Math.copySign(1.0, d) == -1.0) // value is negative,
|
||
|
|
answer.append("-"); // so append sign info
|
||
|
|
|
||
|
|
answer.append("0x");
|
||
|
|
|
||
|
|
d = Math.abs(d);
|
||
|
|
|
||
|
|
if(d == 0.0) {
|
||
|
|
answer.append("0.0p0");
|
||
|
|
} else {
|
||
|
|
boolean subnormal = (d < Double.MIN_NORMAL);
|
||
|
|
|
||
|
|
// Isolate significand bits and OR in a high-order bit
|
||
|
|
// so that the string representation has a known
|
||
|
|
// length.
|
||
|
|
long signifBits = (Double.doubleToLongBits(d)
|
||
|
|
& DoubleConsts.SIGNIF_BIT_MASK) |
|
||
|
|
0x1000000000000000L;
|
||
|
|
|
||
|
|
// Subnormal values have a 0 implicit bit; normal
|
||
|
|
// values have a 1 implicit bit.
|
||
|
|
answer.append(subnormal ? "0." : "1.");
|
||
|
|
|
||
|
|
// Isolate the low-order 13 digits of the hex
|
||
|
|
// representation. If all the digits are zero,
|
||
|
|
// replace with a single 0; otherwise, remove all
|
||
|
|
// trailing zeros.
|
||
|
|
String signif = Long.toHexString(signifBits).substring(3,16);
|
||
|
|
answer.append(signif.equals("0000000000000") ? // 13 zeros
|
||
|
|
"0":
|
||
|
|
signif.replaceFirst("0{1,12}$", ""));
|
||
|
|
|
||
|
|
answer.append('p');
|
||
|
|
// If the value is subnormal, use the E_min exponent
|
||
|
|
// value for double; otherwise, extract and report d's
|
||
|
|
// exponent (the representation of a subnormal uses
|
||
|
|
// E_min -1).
|
||
|
|
answer.append(subnormal ?
|
||
|
|
Double.MIN_EXPONENT:
|
||
|
|
Math.getExponent(d));
|
||
|
|
}
|
||
|
|
return answer.toString();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a {@code Double} object holding the
|
||
|
|
* {@code double} value represented by the argument string
|
||
|
|
* {@code s}.
|
||
|
|
*
|
||
|
|
* <p>If {@code s} is {@code null}, then a
|
||
|
|
* {@code NullPointerException} is thrown.
|
||
|
|
*
|
||
|
|
* <p>Leading and trailing whitespace characters in {@code s}
|
||
|
|
* are ignored. Whitespace is removed as if by the {@link
|
||
|
|
* String#trim} method; that is, both ASCII space and control
|
||
|
|
* characters are removed. The rest of {@code s} should
|
||
|
|
* constitute a <i>FloatValue</i> as described by the lexical
|
||
|
|
* syntax rules:
|
||
|
|
*
|
||
|
|
* <blockquote>
|
||
|
|
* <dl>
|
||
|
|
* <dt><i>FloatValue:</i>
|
||
|
|
* <dd><i>Sign<sub>opt</sub></i> {@code NaN}
|
||
|
|
* <dd><i>Sign<sub>opt</sub></i> {@code Infinity}
|
||
|
|
* <dd><i>Sign<sub>opt</sub> FloatingPointLiteral</i>
|
||
|
|
* <dd><i>Sign<sub>opt</sub> HexFloatingPointLiteral</i>
|
||
|
|
* <dd><i>SignedInteger</i>
|
||
|
|
* </dl>
|
||
|
|
*
|
||
|
|
* <dl>
|
||
|
|
* <dt><i>HexFloatingPointLiteral</i>:
|
||
|
|
* <dd> <i>HexSignificand BinaryExponent FloatTypeSuffix<sub>opt</sub></i>
|
||
|
|
* </dl>
|
||
|
|
*
|
||
|
|
* <dl>
|
||
|
|
* <dt><i>HexSignificand:</i>
|
||
|
|
* <dd><i>HexNumeral</i>
|
||
|
|
* <dd><i>HexNumeral</i> {@code .}
|
||
|
|
* <dd>{@code 0x} <i>HexDigits<sub>opt</sub>
|
||
|
|
* </i>{@code .}<i> HexDigits</i>
|
||
|
|
* <dd>{@code 0X}<i> HexDigits<sub>opt</sub>
|
||
|
|
* </i>{@code .} <i>HexDigits</i>
|
||
|
|
* </dl>
|
||
|
|
*
|
||
|
|
* <dl>
|
||
|
|
* <dt><i>BinaryExponent:</i>
|
||
|
|
* <dd><i>BinaryExponentIndicator SignedInteger</i>
|
||
|
|
* </dl>
|
||
|
|
*
|
||
|
|
* <dl>
|
||
|
|
* <dt><i>BinaryExponentIndicator:</i>
|
||
|
|
* <dd>{@code p}
|
||
|
|
* <dd>{@code P}
|
||
|
|
* </dl>
|
||
|
|
*
|
||
|
|
* </blockquote>
|
||
|
|
*
|
||
|
|
* where <i>Sign</i>, <i>FloatingPointLiteral</i>,
|
||
|
|
* <i>HexNumeral</i>, <i>HexDigits</i>, <i>SignedInteger</i> and
|
||
|
|
* <i>FloatTypeSuffix</i> are as defined in the lexical structure
|
||
|
|
* sections of
|
||
|
|
* <cite>The Java Language Specification</cite>,
|
||
|
|
* except that underscores are not accepted between digits.
|
||
|
|
* If {@code s} does not have the form of
|
||
|
|
* a <i>FloatValue</i>, then a {@code NumberFormatException}
|
||
|
|
* is thrown. Otherwise, {@code s} is regarded as
|
||
|
|
* representing an exact decimal value in the usual
|
||
|
|
* "computerized scientific notation" or as an exact
|
||
|
|
* hexadecimal value; this exact numerical value is then
|
||
|
|
* conceptually converted to an "infinitely precise"
|
||
|
|
* binary value that is then rounded to type {@code double}
|
||
|
|
* by the usual round-to-nearest rule of IEEE 754 floating-point
|
||
|
|
* arithmetic, which includes preserving the sign of a zero
|
||
|
|
* value.
|
||
|
|
*
|
||
|
|
* Note that the round-to-nearest rule also implies overflow and
|
||
|
|
* underflow behaviour; if the exact value of {@code s} is large
|
||
|
|
* enough in magnitude (greater than or equal to ({@link
|
||
|
|
* #MAX_VALUE} + {@link Math#ulp(double) ulp(MAX_VALUE)}/2),
|
||
|
|
* rounding to {@code double} will result in an infinity and if the
|
||
|
|
* exact value of {@code s} is small enough in magnitude (less
|
||
|
|
* than or equal to {@link #MIN_VALUE}/2), rounding to float will
|
||
|
|
* result in a zero.
|
||
|
|
*
|
||
|
|
* Finally, after rounding a {@code Double} object representing
|
||
|
|
* this {@code double} value is returned.
|
||
|
|
*
|
||
|
|
* <p> To interpret localized string representations of a
|
||
|
|
* floating-point value, use subclasses of {@link
|
||
|
|
* java.text.NumberFormat}.
|
||
|
|
*
|
||
|
|
* <p>Note that trailing format specifiers, specifiers that
|
||
|
|
* determine the type of a floating-point literal
|
||
|
|
* ({@code 1.0f} is a {@code float} value;
|
||
|
|
* {@code 1.0d} is a {@code double} value), do
|
||
|
|
* <em>not</em> influence the results of this method. In other
|
||
|
|
* words, the numerical value of the input string is converted
|
||
|
|
* directly to the target floating-point type. The two-step
|
||
|
|
* sequence of conversions, string to {@code float} followed
|
||
|
|
* by {@code float} to {@code double}, is <em>not</em>
|
||
|
|
* equivalent to converting a string directly to
|
||
|
|
* {@code double}. For example, the {@code float}
|
||
|
|
* literal {@code 0.1f} is equal to the {@code double}
|
||
|
|
* value {@code 0.10000000149011612}; the {@code float}
|
||
|
|
* literal {@code 0.1f} represents a different numerical
|
||
|
|
* value than the {@code double} literal
|
||
|
|
* {@code 0.1}. (The numerical value 0.1 cannot be exactly
|
||
|
|
* represented in a binary floating-point number.)
|
||
|
|
*
|
||
|
|
* <p>To avoid calling this method on an invalid string and having
|
||
|
|
* a {@code NumberFormatException} be thrown, the regular
|
||
|
|
* expression below can be used to screen the input string:
|
||
|
|
*
|
||
|
|
* <pre>{@code
|
||
|
|
* final String Digits = "(\\p{Digit}+)";
|
||
|
|
* final String HexDigits = "(\\p{XDigit}+)";
|
||
|
|
* // an exponent is 'e' or 'E' followed by an optionally
|
||
|
|
* // signed decimal integer.
|
||
|
|
* final String Exp = "[eE][+-]?"+Digits;
|
||
|
|
* final String fpRegex =
|
||
|
|
* ("[\\x00-\\x20]*"+ // Optional leading "whitespace"
|
||
|
|
* "[+-]?(" + // Optional sign character
|
||
|
|
* "NaN|" + // "NaN" string
|
||
|
|
* "Infinity|" + // "Infinity" string
|
||
|
|
*
|
||
|
|
* // A decimal floating-point string representing a finite positive
|
||
|
|
* // number without a leading sign has at most five basic pieces:
|
||
|
|
* // Digits . Digits ExponentPart FloatTypeSuffix
|
||
|
|
* //
|
||
|
|
* // Since this method allows integer-only strings as input
|
||
|
|
* // in addition to strings of floating-point literals, the
|
||
|
|
* // two sub-patterns below are simplifications of the grammar
|
||
|
|
* // productions from section 3.10.2 of
|
||
|
|
* // The Java Language Specification.
|
||
|
|
*
|
||
|
|
* // Digits ._opt Digits_opt ExponentPart_opt FloatTypeSuffix_opt
|
||
|
|
* "((("+Digits+"(\\.)?("+Digits+"?)("+Exp+")?)|"+
|
||
|
|
*
|
||
|
|
* // . Digits ExponentPart_opt FloatTypeSuffix_opt
|
||
|
|
* "(\\.("+Digits+")("+Exp+")?)|"+
|
||
|
|
*
|
||
|
|
* // Hexadecimal strings
|
||
|
|
* "((" +
|
||
|
|
* // 0[xX] HexDigits ._opt BinaryExponent FloatTypeSuffix_opt
|
||
|
|
* "(0[xX]" + HexDigits + "(\\.)?)|" +
|
||
|
|
*
|
||
|
|
* // 0[xX] HexDigits_opt . HexDigits BinaryExponent FloatTypeSuffix_opt
|
||
|
|
* "(0[xX]" + HexDigits + "?(\\.)" + HexDigits + ")" +
|
||
|
|
*
|
||
|
|
* ")[pP][+-]?" + Digits + "))" +
|
||
|
|
* "[fFdD]?))" +
|
||
|
|
* "[\\x00-\\x20]*");// Optional trailing "whitespace"
|
||
|
|
*
|
||
|
|
* if (Pattern.matches(fpRegex, myString))
|
||
|
|
* Double.valueOf(myString); // Will not throw NumberFormatException
|
||
|
|
* else {
|
||
|
|
* // Perform suitable alternative action
|
||
|
|
* }
|
||
|
|
* }</pre>
|
||
|
|
*
|
||
|
|
* @param s the string to be parsed.
|
||
|
|
* @return a {@code Double} object holding the value
|
||
|
|
* represented by the {@code String} argument.
|
||
|
|
* @throws NumberFormatException if the string does not contain a
|
||
|
|
* parsable number.
|
||
|
|
*/
|
||
|
|
public static Double valueOf(String s) throws NumberFormatException {
|
||
|
|
return new Double(parseDouble(s));
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a {@code Double} instance representing the specified
|
||
|
|
* {@code double} value.
|
||
|
|
* If a new {@code Double} instance is not required, this method
|
||
|
|
* should generally be used in preference to the constructor
|
||
|
|
* {@link #Double(double)}, as this method is likely to yield
|
||
|
|
* significantly better space and time performance by caching
|
||
|
|
* frequently requested values.
|
||
|
|
*
|
||
|
|
* @param d a double value.
|
||
|
|
* @return a {@code Double} instance representing {@code d}.
|
||
|
|
* @since 1.5
|
||
|
|
*/
|
||
|
|
@IntrinsicCandidate
|
||
|
|
public static Double valueOf(double d) {
|
||
|
|
return new Double(d);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a new {@code double} initialized to the value
|
||
|
|
* represented by the specified {@code String}, as performed
|
||
|
|
* by the {@code valueOf} method of class
|
||
|
|
* {@code Double}.
|
||
|
|
*
|
||
|
|
* @param s the string to be parsed.
|
||
|
|
* @return the {@code double} value represented by the string
|
||
|
|
* argument.
|
||
|
|
* @throws NullPointerException if the string is null
|
||
|
|
* @throws NumberFormatException if the string does not contain
|
||
|
|
* a parsable {@code double}.
|
||
|
|
* @see java.lang.Double#valueOf(String)
|
||
|
|
* @since 1.2
|
||
|
|
*/
|
||
|
|
public static double parseDouble(String s) throws NumberFormatException {
|
||
|
|
return FloatingDecimal.parseDouble(s);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns {@code true} if the specified number is a
|
||
|
|
* Not-a-Number (NaN) value, {@code false} otherwise.
|
||
|
|
*
|
||
|
|
* @param v the value to be tested.
|
||
|
|
* @return {@code true} if the value of the argument is NaN;
|
||
|
|
* {@code false} otherwise.
|
||
|
|
*/
|
||
|
|
public static boolean isNaN(double v) {
|
||
|
|
return (v != v);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns {@code true} if the specified number is infinitely
|
||
|
|
* large in magnitude, {@code false} otherwise.
|
||
|
|
*
|
||
|
|
* @param v the value to be tested.
|
||
|
|
* @return {@code true} if the value of the argument is positive
|
||
|
|
* infinity or negative infinity; {@code false} otherwise.
|
||
|
|
*/
|
||
|
|
public static boolean isInfinite(double v) {
|
||
|
|
return (v == POSITIVE_INFINITY) || (v == NEGATIVE_INFINITY);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns {@code true} if the argument is a finite floating-point
|
||
|
|
* value; returns {@code false} otherwise (for NaN and infinity
|
||
|
|
* arguments).
|
||
|
|
*
|
||
|
|
* @param d the {@code double} value to be tested
|
||
|
|
* @return {@code true} if the argument is a finite
|
||
|
|
* floating-point value, {@code false} otherwise.
|
||
|
|
* @since 1.8
|
||
|
|
*/
|
||
|
|
public static boolean isFinite(double d) {
|
||
|
|
return Math.abs(d) <= Double.MAX_VALUE;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* The value of the Double.
|
||
|
|
*
|
||
|
|
* @serial
|
||
|
|
*/
|
||
|
|
private final double value;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Constructs a newly allocated {@code Double} object that
|
||
|
|
* represents the primitive {@code double} argument.
|
||
|
|
*
|
||
|
|
* @param value the value to be represented by the {@code Double}.
|
||
|
|
*
|
||
|
|
* @deprecated
|
||
|
|
* It is rarely appropriate to use this constructor. The static factory
|
||
|
|
* {@link #valueOf(double)} is generally a better choice, as it is
|
||
|
|
* likely to yield significantly better space and time performance.
|
||
|
|
*/
|
||
|
|
// Android-changed: not yet forRemoval on Android.
|
||
|
|
@Deprecated(since="9"/*, forRemoval = true*/)
|
||
|
|
public Double(double value) {
|
||
|
|
this.value = value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Constructs a newly allocated {@code Double} object that
|
||
|
|
* represents the floating-point value of type {@code double}
|
||
|
|
* represented by the string. The string is converted to a
|
||
|
|
* {@code double} value as if by the {@code valueOf} method.
|
||
|
|
*
|
||
|
|
* @param s a string to be converted to a {@code Double}.
|
||
|
|
* @throws NumberFormatException if the string does not contain a
|
||
|
|
* parsable number.
|
||
|
|
*
|
||
|
|
* @deprecated
|
||
|
|
* It is rarely appropriate to use this constructor.
|
||
|
|
* Use {@link #parseDouble(String)} to convert a string to a
|
||
|
|
* {@code double} primitive, or use {@link #valueOf(String)}
|
||
|
|
* to convert a string to a {@code Double} object.
|
||
|
|
*/
|
||
|
|
// Android-changed: not yet forRemoval on Android.
|
||
|
|
@Deprecated(since="9"/*, forRemoval = true */)
|
||
|
|
public Double(String s) throws NumberFormatException {
|
||
|
|
value = parseDouble(s);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns {@code true} if this {@code Double} value is
|
||
|
|
* a Not-a-Number (NaN), {@code false} otherwise.
|
||
|
|
*
|
||
|
|
* @return {@code true} if the value represented by this object is
|
||
|
|
* NaN; {@code false} otherwise.
|
||
|
|
*/
|
||
|
|
public boolean isNaN() {
|
||
|
|
return isNaN(value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns {@code true} if this {@code Double} value is
|
||
|
|
* infinitely large in magnitude, {@code false} otherwise.
|
||
|
|
*
|
||
|
|
* @return {@code true} if the value represented by this object is
|
||
|
|
* positive infinity or negative infinity;
|
||
|
|
* {@code false} otherwise.
|
||
|
|
*/
|
||
|
|
public boolean isInfinite() {
|
||
|
|
return isInfinite(value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a string representation of this {@code Double} object.
|
||
|
|
* The primitive {@code double} value represented by this
|
||
|
|
* object is converted to a string exactly as if by the method
|
||
|
|
* {@code toString} of one argument.
|
||
|
|
*
|
||
|
|
* @return a {@code String} representation of this object.
|
||
|
|
* @see java.lang.Double#toString(double)
|
||
|
|
*/
|
||
|
|
public String toString() {
|
||
|
|
return toString(value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the value of this {@code Double} as a {@code byte}
|
||
|
|
* after a narrowing primitive conversion.
|
||
|
|
*
|
||
|
|
* @return the {@code double} value represented by this object
|
||
|
|
* converted to type {@code byte}
|
||
|
|
* @jls 5.1.3 Narrowing Primitive Conversion
|
||
|
|
* @since 1.1
|
||
|
|
*/
|
||
|
|
public byte byteValue() {
|
||
|
|
return (byte)value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the value of this {@code Double} as a {@code short}
|
||
|
|
* after a narrowing primitive conversion.
|
||
|
|
*
|
||
|
|
* @return the {@code double} value represented by this object
|
||
|
|
* converted to type {@code short}
|
||
|
|
* @jls 5.1.3 Narrowing Primitive Conversion
|
||
|
|
* @since 1.1
|
||
|
|
*/
|
||
|
|
public short shortValue() {
|
||
|
|
return (short)value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the value of this {@code Double} as an {@code int}
|
||
|
|
* after a narrowing primitive conversion.
|
||
|
|
* @jls 5.1.3 Narrowing Primitive Conversion
|
||
|
|
*
|
||
|
|
* @return the {@code double} value represented by this object
|
||
|
|
* converted to type {@code int}
|
||
|
|
*/
|
||
|
|
public int intValue() {
|
||
|
|
return (int)value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the value of this {@code Double} as a {@code long}
|
||
|
|
* after a narrowing primitive conversion.
|
||
|
|
*
|
||
|
|
* @return the {@code double} value represented by this object
|
||
|
|
* converted to type {@code long}
|
||
|
|
* @jls 5.1.3 Narrowing Primitive Conversion
|
||
|
|
*/
|
||
|
|
public long longValue() {
|
||
|
|
return (long)value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the value of this {@code Double} as a {@code float}
|
||
|
|
* after a narrowing primitive conversion.
|
||
|
|
*
|
||
|
|
* @return the {@code double} value represented by this object
|
||
|
|
* converted to type {@code float}
|
||
|
|
* @jls 5.1.3 Narrowing Primitive Conversion
|
||
|
|
* @since 1.0
|
||
|
|
*/
|
||
|
|
public float floatValue() {
|
||
|
|
return (float)value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the {@code double} value of this {@code Double} object.
|
||
|
|
*
|
||
|
|
* @return the {@code double} value represented by this object
|
||
|
|
*/
|
||
|
|
@IntrinsicCandidate
|
||
|
|
public double doubleValue() {
|
||
|
|
return value;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a hash code for this {@code Double} object. The
|
||
|
|
* result is the exclusive OR of the two halves of the
|
||
|
|
* {@code long} integer bit representation, exactly as
|
||
|
|
* produced by the method {@link #doubleToLongBits(double)}, of
|
||
|
|
* the primitive {@code double} value represented by this
|
||
|
|
* {@code Double} object. That is, the hash code is the value
|
||
|
|
* of the expression:
|
||
|
|
*
|
||
|
|
* <blockquote>
|
||
|
|
* {@code (int)(v^(v>>>32))}
|
||
|
|
* </blockquote>
|
||
|
|
*
|
||
|
|
* where {@code v} is defined by:
|
||
|
|
*
|
||
|
|
* <blockquote>
|
||
|
|
* {@code long v = Double.doubleToLongBits(this.doubleValue());}
|
||
|
|
* </blockquote>
|
||
|
|
*
|
||
|
|
* @return a {@code hash code} value for this object.
|
||
|
|
*/
|
||
|
|
@Override
|
||
|
|
public int hashCode() {
|
||
|
|
return Double.hashCode(value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a hash code for a {@code double} value; compatible with
|
||
|
|
* {@code Double.hashCode()}.
|
||
|
|
*
|
||
|
|
* @param value the value to hash
|
||
|
|
* @return a hash code value for a {@code double} value.
|
||
|
|
* @since 1.8
|
||
|
|
*/
|
||
|
|
public static int hashCode(double value) {
|
||
|
|
long bits = doubleToLongBits(value);
|
||
|
|
return (int)(bits ^ (bits >>> 32));
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Compares this object against the specified object. The result
|
||
|
|
* is {@code true} if and only if the argument is not
|
||
|
|
* {@code null} and is a {@code Double} object that
|
||
|
|
* represents a {@code double} that has the same value as the
|
||
|
|
* {@code double} represented by this object. For this
|
||
|
|
* purpose, two {@code double} values are considered to be
|
||
|
|
* the same if and only if the method {@link
|
||
|
|
* #doubleToLongBits(double)} returns the identical
|
||
|
|
* {@code long} value when applied to each.
|
||
|
|
*
|
||
|
|
* @apiNote
|
||
|
|
* This method is defined in terms of {@link
|
||
|
|
* #doubleToLongBits(double)} rather than the {@code ==} operator
|
||
|
|
* on {@code double} values since the {@code ==} operator does
|
||
|
|
* <em>not</em> define an equivalence relation and to satisfy the
|
||
|
|
* {@linkplain Object#equals equals contract} an equivalence
|
||
|
|
* relation must be implemented; see <a
|
||
|
|
* href="#equivalenceRelation">this discussion</a> for details of
|
||
|
|
* floating-point equality and equivalence.
|
||
|
|
*
|
||
|
|
* @see java.lang.Double#doubleToLongBits(double)
|
||
|
|
* @jls 15.21.1 Numerical Equality Operators == and !=
|
||
|
|
*/
|
||
|
|
public boolean equals(Object obj) {
|
||
|
|
return (obj instanceof Double)
|
||
|
|
&& (doubleToLongBits(((Double)obj).value) ==
|
||
|
|
doubleToLongBits(value));
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a representation of the specified floating-point value
|
||
|
|
* according to the IEEE 754 floating-point "double
|
||
|
|
* format" bit layout.
|
||
|
|
*
|
||
|
|
* <p>Bit 63 (the bit that is selected by the mask
|
||
|
|
* {@code 0x8000000000000000L}) represents the sign of the
|
||
|
|
* floating-point number. Bits
|
||
|
|
* 62-52 (the bits that are selected by the mask
|
||
|
|
* {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
|
||
|
|
* (the bits that are selected by the mask
|
||
|
|
* {@code 0x000fffffffffffffL}) represent the significand
|
||
|
|
* (sometimes called the mantissa) of the floating-point number.
|
||
|
|
*
|
||
|
|
* <p>If the argument is positive infinity, the result is
|
||
|
|
* {@code 0x7ff0000000000000L}.
|
||
|
|
*
|
||
|
|
* <p>If the argument is negative infinity, the result is
|
||
|
|
* {@code 0xfff0000000000000L}.
|
||
|
|
*
|
||
|
|
* <p>If the argument is NaN, the result is
|
||
|
|
* {@code 0x7ff8000000000000L}.
|
||
|
|
*
|
||
|
|
* <p>In all cases, the result is a {@code long} integer that, when
|
||
|
|
* given to the {@link #longBitsToDouble(long)} method, will produce a
|
||
|
|
* floating-point value the same as the argument to
|
||
|
|
* {@code doubleToLongBits} (except all NaN values are
|
||
|
|
* collapsed to a single "canonical" NaN value).
|
||
|
|
*
|
||
|
|
* @param value a {@code double} precision floating-point number.
|
||
|
|
* @return the bits that represent the floating-point number.
|
||
|
|
*/
|
||
|
|
@IntrinsicCandidate
|
||
|
|
public static long doubleToLongBits(double value) {
|
||
|
|
if (!isNaN(value)) {
|
||
|
|
return doubleToRawLongBits(value);
|
||
|
|
}
|
||
|
|
return 0x7ff8000000000000L;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns a representation of the specified floating-point value
|
||
|
|
* according to the IEEE 754 floating-point "double
|
||
|
|
* format" bit layout, preserving Not-a-Number (NaN) values.
|
||
|
|
*
|
||
|
|
* <p>Bit 63 (the bit that is selected by the mask
|
||
|
|
* {@code 0x8000000000000000L}) represents the sign of the
|
||
|
|
* floating-point number. Bits
|
||
|
|
* 62-52 (the bits that are selected by the mask
|
||
|
|
* {@code 0x7ff0000000000000L}) represent the exponent. Bits 51-0
|
||
|
|
* (the bits that are selected by the mask
|
||
|
|
* {@code 0x000fffffffffffffL}) represent the significand
|
||
|
|
* (sometimes called the mantissa) of the floating-point number.
|
||
|
|
*
|
||
|
|
* <p>If the argument is positive infinity, the result is
|
||
|
|
* {@code 0x7ff0000000000000L}.
|
||
|
|
*
|
||
|
|
* <p>If the argument is negative infinity, the result is
|
||
|
|
* {@code 0xfff0000000000000L}.
|
||
|
|
*
|
||
|
|
* <p>If the argument is NaN, the result is the {@code long}
|
||
|
|
* integer representing the actual NaN value. Unlike the
|
||
|
|
* {@code doubleToLongBits} method,
|
||
|
|
* {@code doubleToRawLongBits} does not collapse all the bit
|
||
|
|
* patterns encoding a NaN to a single "canonical" NaN
|
||
|
|
* value.
|
||
|
|
*
|
||
|
|
* <p>In all cases, the result is a {@code long} integer that,
|
||
|
|
* when given to the {@link #longBitsToDouble(long)} method, will
|
||
|
|
* produce a floating-point value the same as the argument to
|
||
|
|
* {@code doubleToRawLongBits}.
|
||
|
|
*
|
||
|
|
* @param value a {@code double} precision floating-point number.
|
||
|
|
* @return the bits that represent the floating-point number.
|
||
|
|
* @since 1.3
|
||
|
|
*/
|
||
|
|
@IntrinsicCandidate
|
||
|
|
public static native long doubleToRawLongBits(double value);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the {@code double} value corresponding to a given
|
||
|
|
* bit representation.
|
||
|
|
* The argument is considered to be a representation of a
|
||
|
|
* floating-point value according to the IEEE 754 floating-point
|
||
|
|
* "double format" bit layout.
|
||
|
|
*
|
||
|
|
* <p>If the argument is {@code 0x7ff0000000000000L}, the result
|
||
|
|
* is positive infinity.
|
||
|
|
*
|
||
|
|
* <p>If the argument is {@code 0xfff0000000000000L}, the result
|
||
|
|
* is negative infinity.
|
||
|
|
*
|
||
|
|
* <p>If the argument is any value in the range
|
||
|
|
* {@code 0x7ff0000000000001L} through
|
||
|
|
* {@code 0x7fffffffffffffffL} or in the range
|
||
|
|
* {@code 0xfff0000000000001L} through
|
||
|
|
* {@code 0xffffffffffffffffL}, the result is a NaN. No IEEE
|
||
|
|
* 754 floating-point operation provided by Java can distinguish
|
||
|
|
* between two NaN values of the same type with different bit
|
||
|
|
* patterns. Distinct values of NaN are only distinguishable by
|
||
|
|
* use of the {@code Double.doubleToRawLongBits} method.
|
||
|
|
*
|
||
|
|
* <p>In all other cases, let <i>s</i>, <i>e</i>, and <i>m</i> be three
|
||
|
|
* values that can be computed from the argument:
|
||
|
|
*
|
||
|
|
* <blockquote><pre>{@code
|
||
|
|
* int s = ((bits >> 63) == 0) ? 1 : -1;
|
||
|
|
* int e = (int)((bits >> 52) & 0x7ffL);
|
||
|
|
* long m = (e == 0) ?
|
||
|
|
* (bits & 0xfffffffffffffL) << 1 :
|
||
|
|
* (bits & 0xfffffffffffffL) | 0x10000000000000L;
|
||
|
|
* }</pre></blockquote>
|
||
|
|
*
|
||
|
|
* Then the floating-point result equals the value of the mathematical
|
||
|
|
* expression <i>s</i>·<i>m</i>·2<sup><i>e</i>-1075</sup>.
|
||
|
|
*
|
||
|
|
* <p>Note that this method may not be able to return a
|
||
|
|
* {@code double} NaN with exactly same bit pattern as the
|
||
|
|
* {@code long} argument. IEEE 754 distinguishes between two
|
||
|
|
* kinds of NaNs, quiet NaNs and <i>signaling NaNs</i>. The
|
||
|
|
* differences between the two kinds of NaN are generally not
|
||
|
|
* visible in Java. Arithmetic operations on signaling NaNs turn
|
||
|
|
* them into quiet NaNs with a different, but often similar, bit
|
||
|
|
* pattern. However, on some processors merely copying a
|
||
|
|
* signaling NaN also performs that conversion. In particular,
|
||
|
|
* copying a signaling NaN to return it to the calling method
|
||
|
|
* may perform this conversion. So {@code longBitsToDouble}
|
||
|
|
* may not be able to return a {@code double} with a
|
||
|
|
* signaling NaN bit pattern. Consequently, for some
|
||
|
|
* {@code long} values,
|
||
|
|
* {@code doubleToRawLongBits(longBitsToDouble(start))} may
|
||
|
|
* <i>not</i> equal {@code start}. Moreover, which
|
||
|
|
* particular bit patterns represent signaling NaNs is platform
|
||
|
|
* dependent; although all NaN bit patterns, quiet or signaling,
|
||
|
|
* must be in the NaN range identified above.
|
||
|
|
*
|
||
|
|
* @param bits any {@code long} integer.
|
||
|
|
* @return the {@code double} floating-point value with the same
|
||
|
|
* bit pattern.
|
||
|
|
*/
|
||
|
|
@IntrinsicCandidate
|
||
|
|
public static native double longBitsToDouble(long bits);
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Compares two {@code Double} objects numerically.
|
||
|
|
*
|
||
|
|
* This method imposes a total order on {@code Double} objects
|
||
|
|
* with two differences compared to the incomplete order defined by
|
||
|
|
* the Java language numerical comparison operators ({@code <, <=,
|
||
|
|
* ==, >=, >}) on {@code double} values.
|
||
|
|
*
|
||
|
|
* <ul><li> A NaN is <em>unordered</em> with respect to other
|
||
|
|
* values and unequal to itself under the comparison
|
||
|
|
* operators. This method chooses to define {@code
|
||
|
|
* Double.NaN} to be equal to itself and greater than all
|
||
|
|
* other {@code double} values (including {@code
|
||
|
|
* Double.POSITIVE_INFINITY}).
|
||
|
|
*
|
||
|
|
* <li> Positive zero and negative zero compare equal
|
||
|
|
* numerically, but are distinct and distinguishable values.
|
||
|
|
* This method chooses to define positive zero ({@code +0.0d}),
|
||
|
|
* to be greater than negative zero ({@code -0.0d}).
|
||
|
|
* </ul>
|
||
|
|
|
||
|
|
* This ensures that the <i>natural ordering</i> of {@code Double}
|
||
|
|
* objects imposed by this method is <i>consistent with
|
||
|
|
* equals</i>; see <a href="#equivalenceRelation">this
|
||
|
|
* discussion</a> for details of floating-point comparison and
|
||
|
|
* ordering.
|
||
|
|
*
|
||
|
|
* @param anotherDouble the {@code Double} to be compared.
|
||
|
|
* @return the value {@code 0} if {@code anotherDouble} is
|
||
|
|
* numerically equal to this {@code Double}; a value
|
||
|
|
* less than {@code 0} if this {@code Double}
|
||
|
|
* is numerically less than {@code anotherDouble};
|
||
|
|
* and a value greater than {@code 0} if this
|
||
|
|
* {@code Double} is numerically greater than
|
||
|
|
* {@code anotherDouble}.
|
||
|
|
*
|
||
|
|
* @jls 15.20.1 Numerical Comparison Operators {@code <}, {@code <=}, {@code >}, and {@code >=}
|
||
|
|
* @since 1.2
|
||
|
|
*/
|
||
|
|
public int compareTo(Double anotherDouble) {
|
||
|
|
return Double.compare(value, anotherDouble.value);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Compares the two specified {@code double} values. The sign
|
||
|
|
* of the integer value returned is the same as that of the
|
||
|
|
* integer that would be returned by the call:
|
||
|
|
* <pre>
|
||
|
|
* new Double(d1).compareTo(new Double(d2))
|
||
|
|
* </pre>
|
||
|
|
*
|
||
|
|
* @param d1 the first {@code double} to compare
|
||
|
|
* @param d2 the second {@code double} to compare
|
||
|
|
* @return the value {@code 0} if {@code d1} is
|
||
|
|
* numerically equal to {@code d2}; a value less than
|
||
|
|
* {@code 0} if {@code d1} is numerically less than
|
||
|
|
* {@code d2}; and a value greater than {@code 0}
|
||
|
|
* if {@code d1} is numerically greater than
|
||
|
|
* {@code d2}.
|
||
|
|
* @since 1.4
|
||
|
|
*/
|
||
|
|
public static int compare(double d1, double d2) {
|
||
|
|
if (d1 < d2)
|
||
|
|
return -1; // Neither val is NaN, thisVal is smaller
|
||
|
|
if (d1 > d2)
|
||
|
|
return 1; // Neither val is NaN, thisVal is larger
|
||
|
|
|
||
|
|
// Cannot use doubleToRawLongBits because of possibility of NaNs.
|
||
|
|
long thisBits = Double.doubleToLongBits(d1);
|
||
|
|
long anotherBits = Double.doubleToLongBits(d2);
|
||
|
|
|
||
|
|
return (thisBits == anotherBits ? 0 : // Values are equal
|
||
|
|
(thisBits < anotherBits ? -1 : // (-0.0, 0.0) or (!NaN, NaN)
|
||
|
|
1)); // (0.0, -0.0) or (NaN, !NaN)
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Adds two {@code double} values together as per the + operator.
|
||
|
|
*
|
||
|
|
* @param a the first operand
|
||
|
|
* @param b the second operand
|
||
|
|
* @return the sum of {@code a} and {@code b}
|
||
|
|
* @jls 4.2.4 Floating-Point Operations
|
||
|
|
* @see java.util.function.BinaryOperator
|
||
|
|
* @since 1.8
|
||
|
|
*/
|
||
|
|
public static double sum(double a, double b) {
|
||
|
|
return a + b;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the greater of two {@code double} values
|
||
|
|
* as if by calling {@link Math#max(double, double) Math.max}.
|
||
|
|
*
|
||
|
|
* @param a the first operand
|
||
|
|
* @param b the second operand
|
||
|
|
* @return the greater of {@code a} and {@code b}
|
||
|
|
* @see java.util.function.BinaryOperator
|
||
|
|
* @since 1.8
|
||
|
|
*/
|
||
|
|
public static double max(double a, double b) {
|
||
|
|
return Math.max(a, b);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns the smaller of two {@code double} values
|
||
|
|
* as if by calling {@link Math#min(double, double) Math.min}.
|
||
|
|
*
|
||
|
|
* @param a the first operand
|
||
|
|
* @param b the second operand
|
||
|
|
* @return the smaller of {@code a} and {@code b}.
|
||
|
|
* @see java.util.function.BinaryOperator
|
||
|
|
* @since 1.8
|
||
|
|
*/
|
||
|
|
public static double min(double a, double b) {
|
||
|
|
return Math.min(a, b);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Returns an {@link Optional} containing the nominal descriptor for this
|
||
|
|
* instance, which is the instance itself.
|
||
|
|
*
|
||
|
|
* @return an {@link Optional} describing the {@linkplain Double} instance
|
||
|
|
* @since 12
|
||
|
|
* @hide
|
||
|
|
*/
|
||
|
|
@Override
|
||
|
|
public Optional<Double> describeConstable() {
|
||
|
|
return Optional.of(this);
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Resolves this instance as a {@link ConstantDesc}, the result of which is
|
||
|
|
* the instance itself.
|
||
|
|
*
|
||
|
|
* @param lookup ignored
|
||
|
|
* @return the {@linkplain Double} instance
|
||
|
|
* @since 12
|
||
|
|
* @hide
|
||
|
|
*/
|
||
|
|
@Override
|
||
|
|
public Double resolveConstantDesc(MethodHandles.Lookup lookup) {
|
||
|
|
return this;
|
||
|
|
}
|
||
|
|
|
||
|
|
/** use serialVersionUID from JDK 1.0.2 for interoperability */
|
||
|
|
@java.io.Serial
|
||
|
|
private static final long serialVersionUID = -9172774392245257468L;
|
||
|
|
}
|