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 markUsed()32 protected void markUsed() { 33 checkNotUsed(); 34 used = true; 35 } 36 checkNotUsed()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 */ build()50 public abstract T build(); 51 } 52