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