computer.java

运行环境：Win9x/NT/2000/XP/ 软件介绍： 第一次java程序设计的

import java.awt.*;
import java.awt.event.*;

public class Computer implements WindowListener,ActionListener{
     
     private 	Frame f;
     double 	d0,d1,d2,result;
     boolean 	flag=true;
     String 	s,oper;
     TextField 	tf1;
     Panel 		p=new Panel();
     
     public static void main(String args[])
     { 	  Computer e=new Computer();        
          e.go();
     }
     
     public void go(){
          int i;
          result=0;
          s=new String();
          oper=new String("+");
          f=new Frame("计算器");
          MenuBar mb=new MenuBar();
          f.setMenuBar(mb);
          Menu m1=new Menu("编辑");
          Menu m2=new Menu("帮助");
          Menu m3=new Menu("关于");
          mb.add(m1);
          mb.add(m3);
          mb.setHelpMenu(m2);
          tf1=new TextField("",15);
          Button[] b=new Button[21];
          for(i=1;i<21;i++)
          {
		  	b[i]=new Button();
          	b[i].setFont(new Font("仿宋",0,16));
          }
          b[1].setLabel("退格");
          b[2].setLabel("CE");
          b[3].setLabel("C");
          b[4].setLabel("/");
          b[5].setLabel("7");
          b[6].setLabel("8");
          b[7].setLabel("9");
          b[8].setLabel("*");
          b[9].setLabel("4");
          b[10].setLabel("5");
          b[11].setLabel("6");
          b[12].setLabel("-");
          b[13].setLabel("1");
          b[14].setLabel("2");
          b[15].setLabel("3");
          b[16].setLabel("+");
          b[17].setLabel("0");
          b[18].setLabel("+/-");
          b[19].setLabel(".");
          b[20].setLabel("=");
          p.setLayout(new GridLayout(5,4));
          p.setBackground(new Color(80,30,100));
          for(i=1;i<21;i++)
          {	 p.add(b[i]);
          	 b[i].addActionListener(this);
          	 b[i].setBackground(new Color(20,130,180));
  	         b[i].setForeground(Color.yellow);
          }
          for(i=1;i<4;i++)  
		  {
          	 b[i].setBackground(new Color(120,180,170));
  	         b[i].setForeground(Color.blue);
          }
          for(i=1;i<=4;i++)  
          {	  b[i*4].setBackground(new Color(120,180,170));
              b[i*4].setForeground(Color.red);
          }
          b[20].setBackground(Color.red);
          f.addWindowListener(this);
          f.setLayout(new BorderLayout());
          f.add("North",tf1);
          f.add("Center",p);
          f.setSize(200,200);
          f.setVisible(true);
     }  
        
     public void windowClosing(WindowEvent e){System.exit(1);}     
     public void windowOpened(WindowEvent e){}
     public void windowIconified(WindowEvent e){}
     public void windowDeiconified(WindowEvent e){}
     public void windowClosed(WindowEvent e){}
     public void windowActivated(WindowEvent e){}
     public void windowDeactivated(WindowEvent e){}
	 
     public void actionPerformed(ActionEvent e){
     	String i1=tf1.getText();
        	s=e.getActionCommand();
         if(s=="0"| s=="1"|s=="2"|s=="3"|s=="4"|s=="5"|s=="6"|s=="7"|s=="8"|s=="9"|s==".")
         	{	if(flag) tf1.setText(i1+s); 
         		else
         		{	tf1.setText(s);
         			flag=true;
         		}
         	}
         	else if(s=="+"|s=="-"|s=="*"|s=="/")         		
         	{	result=Double.parseDouble(i1);
         		flag=false;
         		oper=s;
         	}
         	else if(s=="=")
         	{	d0=Double.parseDouble(i1);
         		if(oper=="+") 	result+=d0;
         		if(oper=="-") 	result-=d0;
         		if(oper=="*") 	result*=d0;
         		if(oper=="/") 	result/=d0;
         		tf1.setText(Double.toString(result));
         		flag=false;
         	} 
         	else if(s=="CE")
         	{	tf1.setText("");
         		flag=false;
         	}
 			else if(s=="C")
         	{	result=0;
         		tf1.setText("");
         		flag=false;
         	}
         	else if(s=="退格")
         	{	String ss=tf1.getText();
         		int i=ss.length();
         		ss=ss.substring(0,i-1);
         		tf1.setText(ss);         	
         	}
         	else if(s=="+/-")
         	{	d2=-1*Double.parseDouble(tf1.getText());
         		tf1.setText(Double.toString(d2));
         	}
     } 
}