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 package com.android.deskclock;
18 
19 /**
20  * A Predicate can determine a true or false value for any input of its
21  * parameterized type. For example, a {@code RegexPredicate} might implement
22  * {@code Predicate<String>}, and return true for any String that matches its
23  * given regular expression.
24  * <p/>
25  * <p/>
26  * Implementors of Predicate which may cause side effects upon evaluation are
27  * strongly encouraged to state this fact clearly in their API documentation.
28  */
29 public interface Predicate<T> {
30 
apply(T t)31     boolean apply(T t);
32 
33     /**
34      * An implementation of the predicate interface that always returns true.
35      */
36     Predicate TRUE = new Predicate() {
37         @Override
38         public boolean apply(Object o) {
39             return true;
40         }
41     };
42 
43     /**
44      * An implementation of the predicate interface that always returns false.
45      */
46     Predicate FALSE = new Predicate() {
47         @Override
48         public boolean apply(Object o) {
49             return false;
50         }
51     };
52 }