0424 --- 小算盤

import java.awt.*;
import java.awt.event.*;
public class calculating
{
private static Frame frm=new Frame("小算盤");
private static Panel pn1=new Panel(new GridLayout(4,3));
private static Panel pn2=new Panel(new GridLayout(4,1));
private static Label lab=new Label("0",Label.RIGHT);
//依序為清除、加、減、乘、除、等於
private static Button cn,ad,sub,mul,div,amo;
//0~9的數字
private static Button digits[]=new Button[10];
private static long num;//存放結果
private static byte op;//代表運算子

public static void main(String args[])
{
frm.setLayout(null);
frm.setBounds(450,250,160,180);

frm.setResizable(false);
lab.setBounds(20,30,120,20);
lab.setBackground(new Color(240,220,190));
pn1.setBounds(20,60,90,105);
pn2.setBounds(110,60,30,105);
//0~9數字鈕
for(int i=9;i>=0;i--){
digits[i]=new Button(Integer.toString(i));
pn1.add(digits[i]);
digits[i].addActionListener(new ActLis());
}
//清除鈕
cn=new Button("C");
pn1.add(cn);
cn.addActionListener(new ActLis());
//等於鈕
amo=new Button("=");
pn1.add(amo);
amo.addActionListener(new ActLis());
//加鈕
ad=new Button("+");
pn2.add(ad);
ad.addActionListener(new ActLis());
//減鈕
sub=new Button("-");
pn2.add(sub);
sub.addActionListener(new ActLis());
//乘鈕
mul=new Button("*");
pn2.add(mul);
mul.addActionListener(new ActLis());
//除鈕
div=new Button("/");
pn2.add(div);
div.addActionListener(new ActLis());

frm.addWindowListener(new WindowAdapter(){public void
windowClosing(WindowEvent e){System.exit(0);}});
frm.add(lab);
frm.add(pn1);
frm.add(pn2);
frm.setVisible(true);
}

public static class ActLis implements ActionListener
{
public void actionPerformed(ActionEvent e)throws NumberFormatException,ArithmeticException{
long result;//存放由字串轉成的數值

Button btn=(Button) e.getSource();
try{
//處理數值1-9
for(int i=0;i<=9;i++){
if(btn==digits[i]){
output_digit(digits[i]);
break;
}
}
if(btn==cn){
result=0L;//把儲存的結果歸0
num=0L;
op=0;
lab.setText(Long.toString(num));
}else if(btn==ad){//加
save_num(ad);
op=1;
}else if(btn==sub){//減
save_num(sub);
op=2;
}else if(btn==mul){//乘
save_num(mul);
op=3;
}else if(btn==div){//除
save_num(div);
op=4;
}else if(btn==amo){
result=Long.parseLong(lab.getText());

switch(op){
case 1:
num+=result;
break;
case 2:
num-=result;
break;
case 3:
num*=result;
break;
case 4:
num/=result;
break;
default:
}
result=0L;
//輸出運算後的結果到顯示器
lab.setText(Long.toString(num));
}
}catch(NumberFormatException ne){
//捕捉例外
}catch(ArithmeticException ae){
//捕捉被除數是零的例外
}
}
//輸出數值到顯示器
private void output_digit(Button btn){
lab.setText(Long.toString(Long.parseLong(lab.getText()+btn.getLabel())));
}
//把第一組數值儲存起來
private void save_num(Button oper){
num=Long.parseLong(lab.getText());
lab.setText(Long.toString(0L));
}
}
}