Brad Fitzpatrick | cdcb73e | 2010-11-22 22:56:23 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2010 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.util; |
| 18 | |
Artur Satayev | df43959 | 2019-12-10 17:47:53 +0000 | [diff] [blame^] | 19 | import android.compat.annotation.UnsupportedAppUsage; |
Mathew Inwood | 4eb56ab | 2018-08-14 17:24:32 +0100 | [diff] [blame] | 20 | |
Brad Fitzpatrick | cdcb73e | 2010-11-22 22:56:23 -0800 | [diff] [blame] | 21 | /** |
| 22 | * Singleton helper class for lazily initialization. |
| 23 | * |
| 24 | * Modeled after frameworks/base/include/utils/Singleton.h |
| 25 | * |
| 26 | * @hide |
| 27 | */ |
| 28 | public abstract class Singleton<T> { |
Artur Satayev | 751e551 | 2019-11-15 19:12:49 +0000 | [diff] [blame] | 29 | |
| 30 | @UnsupportedAppUsage |
| 31 | public Singleton() { |
| 32 | } |
| 33 | |
Mathew Inwood | 4eb56ab | 2018-08-14 17:24:32 +0100 | [diff] [blame] | 34 | @UnsupportedAppUsage |
Brad Fitzpatrick | cdcb73e | 2010-11-22 22:56:23 -0800 | [diff] [blame] | 35 | private T mInstance; |
| 36 | |
| 37 | protected abstract T create(); |
| 38 | |
Mathew Inwood | 4eb56ab | 2018-08-14 17:24:32 +0100 | [diff] [blame] | 39 | @UnsupportedAppUsage |
Brad Fitzpatrick | cdcb73e | 2010-11-22 22:56:23 -0800 | [diff] [blame] | 40 | public final T get() { |
| 41 | synchronized (this) { |
| 42 | if (mInstance == null) { |
| 43 | mInstance = create(); |
| 44 | } |
| 45 | return mInstance; |
| 46 | } |
| 47 | } |
| 48 | } |