jisuan.java

一个applet程序

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
public class JISUAN extends Applet implements ActionListener
{TextField text1,text2,text3;
 Button button1,button2,button3,button4;
 Label label1,label2,label3;
    public void init()
    {setLayout(null);
     text1=new TextField(10);
     text2=new TextField(10);
     text3=new TextField(10);
     label1=new Label("输入第一个数：",Label.CENTER);
     label2=new Label("输入第二个数：",Label.CENTER);
     label3=new Label("结果是：",Label.CENTER);
     button1=new Button("加");
     button2=new Button("减");
     button3=new Button("乘");
     button4=new Button("除");
     add(text1);
     add(text2);
     add(text3);
     add(button1);
     add(button2);
     add(button3);
     add(button4);
     add(label1);
     add(label2);
     add(label3);
     label1.setBounds(0, 20, 150, 30);
     text1.setBounds(160, 20, 200, 30);
     label2.setBounds(0,80, 150, 30);
     text2.setBounds(160, 80, 200, 30);
     label3.setBounds(0, 140, 150,30);
     text3.setBounds(160, 140, 200, 30);
     button1.setBounds(120, 190, 40, 40);
     button2.setBounds(180, 190, 40, 40);
     button3.setBounds(240, 190, 40, 40);
     button4.setBounds(300, 190, 40, 40);
     button1.addActionListener(this);
     button2.addActionListener(this);
     button3.addActionListener(this);
     button4.addActionListener(this);
    }
    public void actionPerformed(ActionEvent e) 
    {double n;
     if(e.getSource()==button1)
     {double n1,n2;
      n1=Double.valueOf(text1.getText()).doubleValue();
      n2=Double.valueOf(text2.getText()).doubleValue();
      n=n1+n2;
      text3.setText(String.valueOf(n));
     }
     else if(e.getSource()==button2)
     {double n1,n2;
      n1=Double.valueOf(text1.getText()).doubleValue();
      n2=Double.valueOf(text2.getText()).doubleValue();
      n=n1-n2;
      text3.setText(String.valueOf(n));
     }
     else if(e.getSource()==button3)
     {double n1,n2;
      n1=Double.valueOf(text1.getText()).doubleValue();
      n2=Double.valueOf(text2.getText()).doubleValue();
      n=n1*n2;
      text3.setText(String.valueOf(n));
     }
     else if(e.getSource()==button4)
     {double n1,n2;
      n1=Double.valueOf(text1.getText()).doubleValue();
      n2=Double.valueOf(text2.getText()).doubleValue();
      n=n1/n2;
      text3.setText(String.valueOf(n));
     }
    }
}