简易计算器源代码分享

package MyProjects;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Calculator extends JFrame implements ActionListener{

private JPanel jPanel1,jPanel2;
private JTextField resultField;
private JButton s1,s2,s3,s4,s5,s6,s7,s8,s9,s0,b1,b2,b3,b4,f1,f2;
private boolean end,add,sub,mul,div;
private double num1,num2;
private String str;
//构造方法
public Calculator()
{
super("达志计算器");
setSize(300,240);
Container con = getContentPane();
con.setLayout(new BorderLayout());
jPanel1 = new JPanel();
jPanel1.setLayout(new GridLayout(1,1));   //创建具有指定行数和列数的网格布局
jPanel2 = new JPanel();
jPanel2.setLayout(new GridLayout(4,4));
resultField = new JTextField("0");
jPanel1.add(resultField);
con.add(jPanel1,BorderLayout.NORTH);
s1=new JButton(" 1 "); s1.addActionListener(this);
s2=new JButton(" 2 "); s2.addActionListener(this);
s3=new JButton(" 3 "); s3.addActionListener(this);

s4=new JButton(" 4 "); s4.addActionListener(this);
s5=new JButton(" 5 "); s5.addActionListener(this);
s6=new JButton(" 6 "); s6.addActionListener(this);
s7=new JButton(" 7 "); s7.addActionListener(this);
s8=new JButton(" 8 "); s8.addActionListener(this);
s9=new JButton(" 9 "); s9.addActionListener(this);
s0=new JButton(" 0 "); s0.addActionListener(this);
b1=new JButton(" + "); b1.addActionListener(this);
b2=new JButton(" - "); b2.addActionListener(this);
b3=new JButton(" * "); b3.addActionListener(this);
b4=new JButton(" / "); b4.addActionListener(this);
f1=new JButton(" . "); f1.addActionListener(this);
f2=new JButton(" = "); f2.addActionListener(this);
jPanel2.add(s1);     jPanel2.add(s2);
jPanel2.add(s3);     jPanel2.add(b1);
jPanel2.add(s4);     jPanel2.add(s5);
jPanel2.add(s6);     jPanel2.add(b2);
jPanel2.add(s7);     jPanel2.add(s8);
jPanel2.add(s9);     jPanel2.add(b3);
jPanel2.add(s0);     jPanel2.add(f1);
jPanel2.add(f2);     jPanel2.add(b4);
con.add(jPanel2,BorderLayout.CENTER);
}

//显示输入的数字
    public void num(int i)
{
String s  = null;
s = String.valueOf(i);   //返回 int 参数的字符串表示形式。
if(end)                 //如果数字输入结束，则将文本框置零，重新输入