/* | |
* Copyright 1999-2011 Alibaba Group. | |
* | |
* Licensed under the Apache License, Version 2.0 (the "License"); | |
* you may not use this file except in compliance with the License. | |
* You may obtain a copy of the License at | |
* | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* | |
* Unless required by applicable law or agreed to in writing, software | |
* distributed under the License is distributed on an "AS IS" BASIS, | |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
* See the License for the specific language governing permissions and | |
* limitations under the License. | |
*/ | |
package com.alibaba.dubbo.common.utils; | |
import java.util.ArrayList; | |
import java.util.EmptyStackException; | |
import java.util.List; | |
/** | |
* Stack. | |
* | |
* @author qian.lei | |
*/ | |
public class Stack<E> | |
{ | |
private int mSize = 0; | |
private List<E> mElements = new ArrayList<E>(); | |
public Stack(){} | |
/** | |
* push. | |
* | |
* @param ele | |
*/ | |
public void push(E ele) | |
{ | |
if( mElements.size() > mSize ) | |
mElements.set(mSize, ele); | |
else | |
mElements.add(ele); | |
mSize++; | |
} | |
/** | |
* pop. | |
* | |
* @return the last element. | |
*/ | |
public E pop() | |
{ | |
if( mSize == 0 ) | |
throw new EmptyStackException(); | |
return mElements.set(--mSize, null); | |
} | |
/** | |
* peek. | |
* | |
* @return the last element. | |
*/ | |
public E peek() | |
{ | |
if( mSize == 0 ) | |
throw new EmptyStackException(); | |
return mElements.get(mSize-1); | |
} | |
/** | |
* get. | |
* | |
* @param index index. | |
* @return element. | |
*/ | |
public E get(int index) | |
{ | |
if( index >= mSize ) | |
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + mSize); | |
return index < 0 ? mElements.get(index+mSize) : mElements.get(index); | |
} | |
/** | |
* set. | |
* | |
* @param index index. | |
* @param value element. | |
* @return old element. | |
*/ | |
public E set(int index, E value) | |
{ | |
if( index >= mSize ) | |
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + mSize); | |
return mElements.set(index < 0 ? index + mSize : index, value); | |
} | |
/** | |
* remove. | |
* | |
* @param index | |
* @return element | |
*/ | |
public E remove(int index) | |
{ | |
if( index >= mSize ) | |
throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + mSize); | |
E ret = mElements.remove(index < 0 ? index + mSize : index); | |
mSize--; | |
return ret; | |
} | |
/** | |
* get stack size. | |
* | |
* @return size. | |
*/ | |
public int size() | |
{ | |
return mSize; | |
} | |
/** | |
* is empty. | |
* | |
* @return empty or not. | |
*/ | |
public boolean isEmpty() | |
{ | |
return mSize == 0; | |
} | |
/** | |
* clear stack. | |
*/ | |
public void clear() | |
{ | |
mSize = 0; | |
mElements.clear(); | |
} | |
} |