1/*
2 * Copyright (C) 2016 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
17package com.android.launcher3.util;
18
19import java.util.ArrayList;
20import java.util.HashMap;
21
22/**
23 * A utility map from keys to an ArrayList of values.
24 */
25public class MultiHashMap<K, V> extends HashMap<K, ArrayList<V>> {
26
27    public MultiHashMap() { }
28
29    public MultiHashMap(int size) {
30        super(size);
31    }
32
33    public void addToList(K key, V value) {
34        ArrayList<V> list = get(key);
35        if (list == null) {
36            list = new ArrayList<>();
37            list.add(value);
38            put(key, list);
39        } else {
40            list.add(value);
41        }
42    }
43
44    @Override
45    public MultiHashMap<K, V> clone() {
46        MultiHashMap<K, V> map = new MultiHashMap<>(size());
47        for (Entry<K, ArrayList<V>> entry : entrySet()) {
48            map.put(entry.getKey(), new ArrayList<V>(entry.getValue()));
49        }
50        return map;
51    }
52}
53