Object Stack
/*
* @(#)$Id: ObjectStack.java 3619 2008-03-26 07:23:03Z yui $
*
* Copyright 2006-2008 Makoto YUI
*
* 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.
*
* Contributors:
* Makoto YUI - initial porting
*/
//package xbird.util.collections;
import java.io.Serializable;
/**
* Light-weight ObjectStack implementation.
* <DIV lang="en"></DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
*/
public final class ObjectStack implements Serializable {
private static final long serialVersionUID = -1652603821997551249L;
public static final int DEFAULT_SIZE = 12;
private Object[] stack;
private int counter = 0;
public ObjectStack() {
this(DEFAULT_SIZE);
}
public ObjectStack(int size) {
this.stack = new Object[size];
}
public void push(Object value) {
ensureCapacity(counter + 1);
stack[counter++] = value;
}
public Object pop() {
Object poped = stack[--counter];
stack[counter] = null;
return poped;
}
public Object get(int at) {
if(at >= counter || at < 0) {
throw new IllegalArgumentException("Out of index: " + at);
}
return stack[at];
}
public boolean isEmpty() {
return counter == 0;
}
public int size() {
return counter;
}
public Object peek() {
return counter == 0 ? null : stack[counter - 1];
}
public void clear() {
for(int i = 0; i < counter; i++) {
stack[i] = null;
}
counter = 0;
}
@Override
public String toString() {
final StringBuilder buf = new StringBuilder();
buf.append('[');
for(int i = 0; i < counter; i++) {
if (i != 0) {
buf.append(", ");
}
buf.append(stack[i]);
}
buf.append(']');
return buf.toString();
}
private void ensureCapacity(int minCapacity) {
int oldCapacity = stack.length;
if (minCapacity > oldCapacity) {
int newCapacity = oldCapacity * 2;
if (newCapacity < minCapacity) {
newCapacity = minCapacity;
}
Object[] newStack = new Object[newCapacity];
System.arraycopy(stack, 0, newStack, 0, counter);
this.stack = newStack;
}
}
}
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