//创建堆栈节点类
class StackElement...{ 
int data; //存放数据 StackElement nextElement; //指下一节点的指针 
StackElement(int data)...{ this.data=data; this.nextElement=null;
} public int Value()...{ return data; }
}//创建堆栈类class Stack...{ StackElement top; //栈顶指针 Stack()...{ top=null; } public void push(int data)...{ if (top==null)...{ top=new StackElement(data); top.nextElement=null; return; } StackElement temp=new StackElement(data); temp.nextElement=top; top=temp; } public int pop()...{ if (top==null)...{ return -1; } int temp=top.Value(); top=top.nextElement; return temp; } public boolean isEmpty()...{ return top==null; }}//创建堆栈实例public class StackDemo...{ public static void main(String[] args)...{ Stack q=new Stack(); int[] intArray=...{31, 53, 8, 21, 9, 23}; for(int i=0; i<intArray.length; i++)...{ q.push(intArray[i]); } System.out.print("the Elements of the Stack q: "); while(!q.isEmpty())...{ System.out.print(q.pop()+" "); } System.out.println(); }}今天 看到了JAVA定义的堆栈类Stack的源代码特来更新下，如下：
/**//* * @(#)Stack.java 1.28 03/12/19 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */package java.util;/** *//** * The <code>Stack</code> class represents a last-in-first-out * (LIFO) stack of objects. It extends class <tt>Vector</tt> with five * operations that allow a vector to be treated as a stack. The usual * <tt>push</tt> and <tt>pop</tt> operations are provided, as well as a * method to <tt>peek</tt> at the top item on the stack, a method to test * for whether the stack is <tt>empty</tt>, and a method to <tt>search</tt> * the stack for an item and discover how far it is from the top. * <p> * When a stack is first created, it contains no items. * * @author Jonathan Payne * @version 1.28, 12/19/03 * @since JDK1.0 */publicclass Stack<E> extends Vector<E> ...{ /** *//** * Creates an empty Stack. */ public Stack() ...{ } /** *//** * Pushes an item onto the top of this stack. This has exactly * the same effect as: * <blockquote><pre> * addElement(item)</pre></blockquote> * * @param item the item to be pushed onto this stack. * @return the <code>item</code> argument. * @see java.util.Vector#addElement */ public E push(E item) ...{ addElement(item); return item; } /** *//** * Removes the object at the top of this stack and returns that * object as the value of this function. * * @return The object at the top of this stack (the last item * of the <tt>Vector</tt> object). * @exception EmptyStackException if this stack is empty. */ public synchronized E pop() ...{ E obj; int len = size(); obj = peek(); removeElementAt(len - 1); return obj; } /** *//** * Looks at the object at the top of this stack without removing it * from the stack. * * @return the object at the top of this stack (the last item * of the <tt>Vector</tt> object). * @exception EmptyStackException if this stack is empty. */ public synchronized E peek() ...{ int len = size(); if (len == 0) throw new EmptyStackException(); return elementAt(len - 1); } /** *//** * Tests if this stack is empty. * * @return <code>true</code> if and only if this stack contains * no items; <code>false</code> otherwise. */ public boolean empty() ...{ return size() == 0; } /** *//** * Returns the 1-based position where an object is on this stack. * If the object <tt>o</tt> occurs as an item in this stack, this * method returns the distance from the top of the stack of the * occurrence nearest the top of the stack; the topmost item on the * stack is considered to be at distance <tt>1</tt>. The <tt>equals</tt> * method is used to compare <tt>o</tt> to the * items in this stack. * * @param o the desired object. * @return the 1-based position from the top of the stack where * the object is located; the return value <code>-1</code> * indicates that the object is not on the stack. */ public synchronized int search(Object o) ...{ int i = lastIndexOf(o); if (i >= 0) ...{ return size() - i; } return -1; } /** *//** use serialVersionUID from JDK 1.0.2 for interoperability */ private static final long serialVersionUID = 1224463164541339165L;}