50 lines
1.3 KiB
Java
50 lines
1.3 KiB
Java
/*
|
|
* Copyright (C) 2010 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
package android.util;
|
|
|
|
import android.compat.annotation.UnsupportedAppUsage;
|
|
|
|
/**
|
|
* Singleton helper class for lazily initialization.
|
|
*
|
|
* Modeled after frameworks/base/include/utils/Singleton.h
|
|
*
|
|
* @hide
|
|
*/
|
|
@android.ravenwood.annotation.RavenwoodKeepWholeClass
|
|
public abstract class Singleton<T> {
|
|
|
|
@UnsupportedAppUsage
|
|
public Singleton() {
|
|
}
|
|
|
|
@UnsupportedAppUsage
|
|
private T mInstance;
|
|
|
|
protected abstract T create();
|
|
|
|
@UnsupportedAppUsage
|
|
public final T get() {
|
|
synchronized (this) {
|
|
if (mInstance == null) {
|
|
mInstance = create();
|
|
}
|
|
return mInstance;
|
|
}
|
|
}
|
|
}
|