1 /*
2  * Copyright (C) 2021 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.managedprovisioning.common;
18 
19 import java.util.HashMap;
20 import java.util.Map;
21 import java.util.Objects;
22 
23 /**
24  * A bi-directional map where the key and value are of the same type.
25  *
26  * @param <T> the type of the elements in this map
27  */
28 public final class HomogenousBiMap<T> {
29     private final Map<T, T> mForwardMap = new HashMap<>();
30     private final Map<T, T> mReverseMap = new HashMap<>();
31 
32     /**
33      * Puts an element to the map.
34      *
35      * @see #getForwardMap()
36      * @see #getReverseMap()
37      */
put(T key, T value)38     public void put(T key, T value) {
39         mForwardMap.put(key, value);
40         mReverseMap.put(value, key);
41     }
42 
43     /**
44      * Returns a copy of the forward map. After {@link #put(Object, Object)} is called, the {@code
45      * key} is in the key set of this map, and the {@code value} is the value list of this map.
46      */
getForwardMap()47     public Map<T, T> getForwardMap() {
48         return new HashMap<>(mForwardMap);
49     }
50 
51     /**
52      * Returns a copy of the reverse map. After {@link #put(Object, Object)} is called, the {@code
53      * value} is the key set of this map, and the {@code key} is the value list of this map.
54      */
getReverseMap()55     public Map<T, T> getReverseMap() {
56         return new HashMap<>(mReverseMap);
57     }
58 
59     /**
60      * Clears the map.
61      */
clear()62     public void clear() {
63         mForwardMap.clear();
64         mReverseMap.clear();
65     }
66 
67     @Override
equals(Object o)68     public boolean equals(Object o) {
69         if (this == o) return true;
70         if (!(o instanceof HomogenousBiMap)) return false;
71         HomogenousBiMap<?> that = (HomogenousBiMap<?>) o;
72         return Objects.equals(mForwardMap, that.mForwardMap) &&
73                 Objects.equals(mReverseMap, that.mReverseMap);
74     }
75 
76     @Override
hashCode()77     public int hashCode() {
78         return Objects.hash(mForwardMap, mReverseMap);
79     }
80 }
81