package calc;

import java.awt.event.ActionEvent;

 import java.awt.event.ActionListener;

 import java.awt.Container;

 import java.awt.FlowLayout;

 import javax.swing.JFrame;

 import javax.swing.JTextField;

 import javax.swing.JButton;

 public class Calc {



     /**

      * @param args

      */

     private static int numClicks=0;

     public static void main(String[] args) {

         // TODO Auto-generated method stub

         final JFrame jf=new JFrame("计算器");

         final Container c=jf.getContentPane();

         c.setLayout(new FlowLayout(FlowLayout.CENTER));

         final JTextField f1=new JTextField(4);

         final JTextField f2=new JTextField(4);

         final JTextField f3=new JTextField(4);

         final JButton b1=new JButton("+");//内部类如果要使用外部类的变量，必须使用final修饰符

         final JButton b2=new JButton("=");

         b1.addActionListener(new ActionListener(){

             public void actionPerformed(ActionEvent e)

             {

                 numClicks++;

                 switch(numClicks%4)

                 {

                 case 0:b1.setText("+");break;

                 case 1:b1.setText("-");break;

                 case 2:b1.setText("*");break;

                 case 3:b1.setText("/");break;

                 }

             }

         });

         b2.addActionListener(new ActionListener(){

             public void actionPerformed(ActionEvent e)

             {

                 int n1=Integer.parseInt(f1.getText());

                 int n2=Integer.parseInt(f2.getText());

                 int n3=n1+n2;

                switch(numClicks%4)

                 {

                 case 0:n3=n1+n2;break;

                 case 1:n3=n1-n2;break;

                 case 2:n3=n1*n2;break;

                 case 3:n3=n1/n2;break;

                 }

                 f3.setText(String.valueOf(n3));

             }

         });

         c.add(f1);

         c.add(b1);

         c.add(f2);

         c.add(b2);

         c.add(f3);

         jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         jf.setSize(400, 80);

         jf.setVisible(true);

     }

 }