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.server.wm;
18 
19 import java.util.ArrayList;
20 
21 /**
22  * An {@link ArrayList} with extended functionality to be used as the children data structure in
23  * {@link WindowContainer}.
24  */
25 class WindowList<E> extends ArrayList<E> {
26 
addFirst(E e)27     void addFirst(E e) {
28         add(0, e);
29     }
30 
peekLast()31     E peekLast() {
32         return size() > 0 ? get(size() - 1) : null;
33     }
34 
peekFirst()35     E peekFirst() {
36         return size() > 0 ? get(0) : null;
37     }
38 }
39