1/*
2 * Copyright (C) 2010 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.layoutlib.bridge.impl;
18
19import java.util.ArrayList;
20
21/**
22 * Custom Stack implementation on top of an {@link ArrayList} instead of
23 * using {@link java.util.Stack} which is on top of a vector.
24 *
25 * @param <T>
26 */
27public class Stack<T> extends ArrayList<T> {
28
29    private static final long serialVersionUID = 1L;
30
31    public Stack() {
32        super();
33    }
34
35    public Stack(int size) {
36        super(size);
37    }
38
39    /**
40     * Pushes the given object to the stack
41     * @param object the object to push
42     */
43    public void push(T object) {
44        add(object);
45    }
46
47    /**
48     * Remove the object at the top of the stack and returns it.
49     * @return the removed object or null if the stack was empty.
50     */
51    public T pop() {
52        if (size() > 0) {
53            return remove(size() - 1);
54        }
55
56        return null;
57    }
58
59    /**
60     * Returns the object at the top of the stack.
61     * @return the object at the top or null if the stack is empty.
62     */
63    public T peek() {
64        if (size() > 0) {
65            return get(size() - 1);
66        }
67
68        return null;
69    }
70}
71