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