swing---编写计算器代码

import javax.swing.JFrame;

import javax.swing.JButton;

import javax.swing.JPanel;

import javax.swing.JTextField;

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.util.EventObject;

public class Calculator extends JFrame implements ActionListener{

 String[] keys={"7","8","9","/","4","5","6",

            "*","1","2","3","-","0",".","=","+"};

 //保存按钮上字符

JButton b[]=new JButton[keys.length];

//按钮数组

JButton clear;

JPanel p=new JPanel();//中间面板

JTextField t=new JTextField("0.0");

//文本框并设置初始值

GridLayout g=new GridLayout(4,4,4,4);

//四行四列，行和列的间距

int j=0;

int action;

double sum=0,num;int i=0;

Calculator(){

setBounds(100,100,300,200);

//设置位置和大小

p.setLayout(g);//面板的布局设置为网格布局

for( int i = 0; i

        b[i] = new JButton(keys[i]);

        b[i].addActionListener(this);

        p.add(b[i]);

    }//实例化按钮，并添加到按钮中

    clear = new JButton("Clear");

    clear.addActionListener(this);

    t.setHorizontalAlignment(JTextField.RIGHT);

    //设置文字显示方式为右对齐

    add(t,"North");

    add(p);

    add(clear,"South");

   setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

pack();

    setVisible(true);

}public static void main(String[] args) {

Calculator f=new Calculator();

public void actionPerformed(ActionEvent a) {

JButton b=(JButton)a.getSource();//求事件的发生源

String s=b.getText();//求事件源上的文字

char c=s.charAt(0);

num=Double.parseDouble(t.getText().trim());

if(c=='+'){

if(j==0)sum=num;

else if(action ==1)sum+=num;

else if(action ==2)sum-=num;

else if(action ==3)sum*=num;

else sum/=num;

t.setText(sum+"");

j++;i=0;action=1;

else if(c=='-'){

if(j==0)sum=num;

else if(action ==1)sum+=num;

else if(action ==2)sum-=num;

else if(action ==3)sum*=num;

else sum/=num;

t.setText(sum+"");

j++;i=0;action=2;

else if(c=='*'){

if(j==0)sum=num;

else if(action ==1)sum+=num;

else if(action ==2)sum-=num;

else if(action ==3)sum*=num;

else sum/=num;

t.setText(sum+"");

j++;i=0;action=3;

else if(c=='/'){

if(j==0)sum=num;

else if(action ==1)sum+=num;

else if(action ==2)sum-=num;

else if(action ==3)sum*=num;

else sum/=num;

t.setText(sum+"");

j++;i=0;action=4;

else if(c=='='){

switch(action){

case 1 :t.setText((sum+=num)+"");break;

case 2 :t.setText((sum-=num)+"");break

case 3 :t.setText((sum*=num)+"");break;

case 4 :t.setText((sum/=num)+"");break;

}

t.setText(sum+"");

j++;i=0;action=0;

else if(c=='.'){

if(t.getText().indexOf('.')==-1)

t.setText(t.getText()+c);

else if(c=='C'){//复位

i=0;j=0;sum=0;action=0;

t.setText("0.0");else {if(i==0)

t.setText("");

t.setText(t.getText()+c);

i++;