import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Caculator extends JFrame implements KeyListener{ //构造Caculator类
private Container content;//构造容器
private JButton bCancel; //清除按钮
private JButton[] b=new JButton[16]; //构造按钮数组
private char LastOp; //操作符号
private boolean Countable; //用于判断是否可计算
private String KeyLabel[]={"7","8","9","/","4","5","6","*","1","2","3","-","0",".","=","+"};
private StringBuffer str;
private JPanel KeyPanel,TextPanel; //按键面板，结果面板
private JTextArea tResult; //用于显示结果的文本域
private double x=0,y=0; //操作数
public Caculator(){
setTitle("袖珍计算器");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
content =getContentPane(); //初始化一个容器
content.setLayout(new BorderLayout()); //设置容器的布局方式
KeyPanel=new JPanel();
TextPanel=new JPanel();
TextPanel.setLayout(new FlowLayout()); //设置TextPanel面板的布局方式
KeyPanel.setLayout(new GridLayout(4,4)); //设置KeyPanel面板的布局方式
tResult=new JTextArea(1,15); //实例化一个JTextArea类
tResult.setEditable(false); //将tResult设置为不可编辑
tResult.setText("0"); //文本域显示为0
tResult.addKeyListener(this); //添加键盘监听器
str=new StringBuffer(); //实例化一个字符串缓冲区
ButtonListener btnListener = new ButtonListener(); //实例化一个ButtonListener类的监听器
for(int i=0;i<16;i++){
b[i] = new JButton(KeyLabel[i]);
b[i].addActionListener(btnListener); //添加ButtonListener类监听器
b[i].addKeyListener(this); //添加键盘监听器
KeyPanel.add(b[i]);
}
bCancel=new JButton("C");
bCancel.addActionListener(btnListener); //添加ButtonListener类监听器
bCancel.addKeyListener(this); //添加键盘监听器
bCancel.setBackground(Color.RED);
LastOp='!'; //若LastOp的值不为'+' '-' '*' '/'中的一个，则约定它的值是 '!'
Countable=false;
TextPanel.add(tResult);
TextPanel.add(bCancel);
content.add("North",TextPanel);
content.add("Center",KeyPanel);
pack();
setResizable(false);
setVisible(true);
}
class ButtonListener implements ActionListener //构造监听器
{
public void actionPerformed(ActionEvent e) {
String s = ((JButton)e.getSource()).getText().trim(); //得到用户按下的按钮上的文本
char c = s.charAt(0); //得到s中索引为0的字符
if(c == 'C') //选择按钮C
{
tResult.setText("0");
str.setLength(0);
LastOp = '!';
Countable = false;
x = 0;
y = 0;
return;
}
if(c == '.') //选择输入小数点
{
if( tResult.getText().trim().indexOf(".") != -1) return;
else
{ str.insert(str.length(),".");
tResult.append(".");
return;
}
}
if(c == '+'||c == '-'||c == '*'||c == '/'||c == '=') //按加减乘除或等号键
{
Caculate(c);
return;
}
//剩下的数字键
tResult.setText(str.append(s).toString());
Countable=true;
}
}
//实现KeyListener监听器
public void keyTyped(KeyEvent ek)
{
char c = ek.getKeyChar(); //获取键盘上按的数字键
if(c=='1'||c=='2'||c=='3'||c=='4'||c=='5'||c=='6'||c=='7'||c=='8'||c=='9'||c=='0')
{
tResult.setText(str.append(c).toString());
Countable=true;
return;
}
if(c =='.') //按小数点
{
if( tResult.getText().trim().indexOf(".") != -1) return;
else
{ str.insert(str.length(),".");
tResult.append(".");
return;
}
}
if((int)c == KeyEvent.VK_DELETE ) //按delete键
{
tResult.setText("0");
str.setLength(0);
LastOp = '!';
Countable = false;
x = 0;
y = 0;
return;
}
if(c == '+'||c == '-'||c == '*'||c == '/'||c == '=') //按加减乘除或等号键
{
Caculate(c);
return;
}
}
public void keyPressed(KeyEvent ek) {}
public void keyReleased(KeyEvent ek) {}
public void Caculate(char c)
{
if(c == '+') //按加号键
{
Add();
return;
}
if( c == '-') //按减号键
{
Minus();
return;
}
if(c == '*') //按乘号键
{
Mul();
return;
}
if(c == '/') //按除号键
{
Div();
return;
}
if(c == '=') //按等号键
{
Equal();
return;
}
}
public void Add(){ //加方法
if(Countable==true && LastOp != '!') //判断是否进行运算
{
y = Double.parseDouble(tResult.getText().trim());
switch(LastOp)
{
case '+' : x = x+y; break;
case '-' : x = x-y; break;
case '*' : x = x*y; break;
case '/' :if(y != 0) x = x/y;
else
{
tResult.setText("除数不能为0");return;
}
}
tResult.setText(""+x);
Countable = false;
}
else x = Double.parseDouble(tResult.getText().trim());
str.setLength(0);
y = 0;
LastOp = '+';
return ;
}
public void Minus(){ //减方法
if(Countable==true && LastOp != '!') //判断是否进行运算
{
y = Double.parseDouble(tResult.getText().trim());
switch(LastOp)
{
case '+' : x = x+y; break;
case '-' : x = x-y; break;
case '*' : x = x*y; break;
case '/' :if(y != 0) x = x/y;
else
{
tResult.setText("除数不能为0");return;
}
}
tResult.setText(""+x);
Countable = false;
}
else x = Double.parseDouble(tResult.getText().trim());
str.setLength(0);
y = 0;
LastOp = '-';
return ;
}
public void Mul(){ //乘方法
if(Countable==true && LastOp != '!') //判断是否进行运算
{
y = Double.parseDouble(tResult.getText().trim());
switch(LastOp)
{
case '+' : x = x+y; break;
case '-' : x = x-y; break;
case '*' : x = x*y; break;
case '/' :if(y != 0) x = x/y;
else
{
tResult.setText("除数不能为0");return;
}
}
tResult.setText(""+x);
Countable = false;
}
else x = Double.parseDouble(tResult.getText().trim());
str.setLength(0);
y = 0;
LastOp = '*';
return ;
}
public void Div() //除方法
{
if(Countable==true && LastOp != '!') //判断是否进行运算
{
y = Double.parseDouble(tResult.getText().trim());
switch(LastOp)
{
case '+' : x = x+y; break;
case '-' : x = x-y; break;
case '*' : x = x*y; break;
case '/' :if(y != 0) x = x/y;
else
{
tResult.setText("除数不能为0");return;
}
}
tResult.setText(""+x);
Countable = false;
}
else x = Double.parseDouble(tResult.getText().trim());
str.setLength(0);
y = 0;
LastOp = '/';
return ;
}
public void Equal() //求结果的方法
{
y = Double.parseDouble(tResult.getText().trim());
switch(LastOp)
{
case '+' : x = x+y; break;
case '-' : x = x-y; break;
case '*' : x = x*y; break;
case '/' :if(y != 0) x = x/y;
else
{
tResult.setText("除数不能为0");return;
}
}
tResult.setText(""+x);
Countable=false;
return;
}
public static void main(String args[])
{
Caculator cal=new Caculator();
}
}
