usestack.java

这是一个用Java语言编的一个小程序

import java.applet.Applet;
import java.awt.*;
import java.util.*;
public class UseStack extends Applet
{
  Stack MyStack;
  Label prompt=new Label("新数据：");
  Button pushBtn=new Button("压栈");
  Button popBtn=new Button("弹栈");
  TextField input=new TextField(5);
  int[]DrawStack=new int[10];
  int[]PoppedOut=new int[20];
  int StackCnt=0;
  int PopCnt=0;
  String msg="";
  public void init()
  {
     MyStack=new Stack();
     add(prompt);add(input);add(pushBtn);add(popBtn);
  }
  public void paint(Graphics g)
  {
     for(int i=0;i<StackCnt;i++)
     {
        g.drawRect(50,200-i*20,80,20);
        g.drawString(Integer.toString(DrawStack[i]),80,215-i*20);
      }
      for(int i=0;i<PopCnt;i++)
         g.drawString(Integer.toString(PoppedOut[i]),200+i*20,100);
       g.drawString("堆栈",70,236);
       g.drawString("栈底",135,225);
       g.drawString("栈顶",160,225-StackCnt*20);
       g.drawString(msg,200,140);
   }
   public boolean action(Event e,Object o)
   {
      if(e.target==pushBtn)
      {
         if(StackCnt<10)
         {
           MyStack.push(new Integer(input.getText()));
           DrawStack[StackCnt++]=Integer.parseInt(input.getText());
           input.setText("");
          }
          else
            msg="输入数据过多，请先弹栈！";
       }
       else if(e.target==popBtn)
       {
          if(!MyStack.empty())
          {
             StackCnt--;
             PoppedOut[PopCnt++]=((Integer)(MyStack.pop())).intValue();
           }
           else
              msg="堆栈已空，不能再弹栈！";
         }
         repaint();
         return true;
     }
}