java压栈出栈？急急急急

[pjkimi]

class Demo<T>{
private T[] item;
private int i;

public Demo(int count){
item=new T[count];
i=0;
}

public void push(T item){
T[i++]=item;
}

public T Pop(){
return T[--i];
}

public static void main(String[] args){
Demo<int> de=new Demo<int>(7);
for(int i=0;i<7;i++){
de.push(i);
}

for(int i=0;i<7;i++){
System.out.print(de.Pop());
}
}
}
我以前搞c#这样可以在java中报错item=new T[count];好像构造函数不能这样写该怎么样实现？

[cursor_wang]

java中Api专门有这个类的．

import java.util.*;
class Demo{
	int count;
	public Demo(int c){
		this.count=c;
	}
	public static void main(String[] args){
		Stack s=new Stack();
		Demo d;
		for(int i=0;i<7;i++){
			d=new Demo(i);
			s.push(d.count);
		}
		for(int i=0;i<7;i++){
			System.out.println(s.pop());
		}
	}
}

[cursor_wang]

api中的stack类源码

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
 */
public
class 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;
}

[梅小西Echo]

对，stack和Vector都有

//实现一个栈操作，将1~12月的英文单词压入栈中，然后在将其取出，使用Java代码实现 [SAP公司2005年10月面试题]
import java.util.*;

public class Stacks
{
	static String[] months = {"January", "February","March","April","May","June",
		                      "July","August", "September", "October", "November", "December"};
	
	public static void stackByStack()
	{
		Stack stk = new Stack();
		for( int i = 0; i < months.length; i++ )
			stk.push( months[i] + " ");
		System.out.println( "stk = " + stk );
		
//		stk.addElement( "The last line " );
//		System.out.println( "element 2 =" + stk.elementAt( 2 ));
		
		System.out.println( "出栈:" );
		while( !stk.empty() )
			System.out.println( stk.pop() );
	}
	
	public static void stackByVector()
	{
		Vector vq = new Vector();
		for( int i = 0; i < months.length; i++ )
			vq.addElement( months[i] + " " );
		
		System.out.println( vq );
		
		if ( vq.isEmpty() )
			System.out.println("为空");
		
		System.out.println("出栈：");
		while( !vq.isEmpty() )
		{
			System.out.println( vq.lastElement() );//如果按先进先出，则改为vq.firstElement()
			vq.removeElement( vq.lastElement() );
		}
		vq.clear();
	}
	
	public static void main(String[] arg)
	{
		stackByStack(); //使用Stack实现
		stackByVector(); //使用Vector实现
	}
}

[michaelye18]

Java API中栈不好

[rwg202315]

java 中的栈不好用，建议你用List接口写一个实现了栈功能的类