Eugene Susla | 6ed45d8 | 2017-01-22 13:52:51 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 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 | |
| 18 | package android.provider; |
| 19 | |
| 20 | /** |
| 21 | * A builder that facilitates prohibiting its use after an instance was created with it. |
| 22 | * |
| 23 | * Suggested usage: |
| 24 | * call {@link #checkNotUsed} in each setter, and {@link #markUsed} in {@link #build} |
| 25 | * |
| 26 | * @param <T> Type of object being built |
| 27 | * @hide |
| 28 | */ |
| 29 | public abstract class OneTimeUseBuilder<T> { |
| 30 | private boolean used = false; |
| 31 | |
| 32 | protected void markUsed() { |
| 33 | checkNotUsed(); |
| 34 | used = true; |
| 35 | } |
| 36 | |
| 37 | protected void checkNotUsed() { |
| 38 | if (used) { |
| 39 | throw new IllegalStateException( |
| 40 | "This Builder should not be reused. Use a new Builder instance instead"); |
| 41 | } |
| 42 | } |
| 43 | |
| 44 | /** |
| 45 | * Builds the instance |
| 46 | * |
| 47 | * Once this method is called, this builder should no longer be used. Any subsequent calls to a |
| 48 | * setter or {@code build()} will throw an exception |
| 49 | */ |
| 50 | public abstract T build(); |
| 51 | } |