计算器

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


public class jh 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 String str;
private double num1,num2;

public jh()
{
super("计算器");
setSize(300,240);
Container con=getContentPane();
con.setLayout(new BorderLayout());
jPanel1=new JPanel();
jPanel1.setLayout(new GridLayout(1,1));
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);

}

public void num(int i)
{
String s = null;
s=String.valueOf(i);
if(end){
//如果数字输入结束，则将文本框置零，重新输入
resultField.setText("0");
end=false;
}
if((resultField.getText()).equals("0")){
//如果文本框的内容为零，则覆盖文本框的内容
resultField.setText(s);

}
else{
//如果文本框的内容不为零，则在内容后面添加数字
str = resultField.getText() + s;
resultField.setText(str);

}
}
public void actionPerformed(ActionEvent e){ //数字事件
if(e.getSource()==s1)
num(1);
else if(e.getSource()==s2)
num(2);
else if(e.getSource()==s3)
num(3);
else if(e.getSource()==s4)
num(4);
else if(e.getSource()==s5)
num(5);
else if(e.getSource()==s6)
num(6);
else if(e.getSource()==s7)
num(7);
else if(e.getSource()==s8)
num(8);
else if(e.getSource()==s9)
num(9);
else if(e.getSource()==s0)
num(0);

//符号事件
else if(e.getSource()==b1)
sign(1);
else if(e.getSource()==b2)
sign(2);
else if(e.getSource()==b3)
sign(3);
else if(e.getSource()==b4)
sign(4);
//等号
else if(e.getSource()==f1){
str=resultField.getText();
if(str.indexOf(".")<=1){
str+=".";
resultField.setText(str);
}
}
else if(e.getSource()==f2){
num2=Double.parseDouble(resultField.getText());



if(add){
num1=num1 + num2;}
else if(sub){
num1=num1 - num2;}
else if(mul){
num1=num1 * num2;}
else if(div){
num1=num1 / num2;}
resultField.setText(String.valueOf(num1));
end=true;
}
}
public void sign(int s)
{
if(s==1)
{
add=true;
sub=false;
mul=false;
div=false;
}
else if(s==2){
add=false;
sub=true;
mul=false;
div=false;
}
else if(s==3){
add=false;
sub=false;
mul=true;
div=false;
}
else if(s==4)
{
add=false;
sub=false;
mul=false;
div=true;
}
num1=Double.parseDouble(resultField.getText());
end=true;
}

public static void main(String[] args){
jh th1=new jh();
th1.show();
}
}