java简单的计算器类

package chap;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Calculator {
private JFrame frame;
private JPanel panel,panelKeys,panelKeys_up,panelKeys_down;
private JTextField textComputer;//计算区域
private JButton buttonBk,buttonC;//退格键和清零键
private JButton button[];//数字键组
private JButton buttonDot,buttonAddSub,buttonAdd,buttonSub,buttonMul,buttonDiv,button1,button2,button3,buttonEqual;
private double result;//计算结果
private final short ADD = 1;
private final short SUB = 2;
private final short MUL = 3;
private final short DIV = 4;
private short operator = -1;//运算符
public Calculator(){
frame = new JFrame("计算机");
frame.setSize(400, 250);
panel = new JPanel();//全局面板
panel.setVisible(true);
frame.setVisible(true);
frame.getContentPane().add(panel);
ActionListener listener = new ComputerActionListener();//按键监听器
//计算区
textComputer = new JTextField(15);
textComputer.setText("");
textComputer.setEditable(false);
textComputer.setBackground(new Color(255,255,255));
//功能键上半部分
panelKeys_up = new JPanel();
panelKeys_up.setLayout(new FlowLayout(FlowLayout.RIGHT));
buttonBk = new JButton("Backspace");
buttonBk.setForeground(new Color(255,0,0));
buttonC = new JButton("C");
buttonC.setForeground(new Color(255,0,0));
buttonBk.addActionListener(listener);
buttonC.addActionListener(listener);
panelKeys_up.add(buttonBk);
panelKeys_up.add(buttonC);
//功能键下半部分
panelKeys_down = new JPanel();
panelKeys_down.setLayout(new GridLayout(4,5));
button = new JButton[10];
for(int i = 0;i < button.length;i++){
button[i] = new JButton(Integer.toString(i));
button[i].setForeground(new Color(255,0,0));
}
buttonAddSub = new JButton("+/-");
buttonAddSub.setForeground(new Color(255,0,0));
buttonAdd = new JButton("+");
buttonAdd.setForeground(new Color(255,0,0));
buttonSub = new JButton("-");
buttonSub.setForeground(new Color(255,0,0));
buttonMul = new JButton("*");
buttonMul.setForeground(new Color(255,0,0));
buttonDiv = new JButton("/");
buttonDiv.setForeground(new Color(255,0,0));
button1 = new JButton();
button2 = new JButton();
button3 = new JButton();
button1.setForeground(new Color(255,0,0));
button2.setForeground(new Color(255,0,0));
button3.setForeground(new Color(255,0,0));
buttonEqual = new JButton("=");
buttonEqual.setForeground(new Color(255,0,0));
buttonAddSub.addActionListener(listener);
buttonAdd.addActionListener(listener);
buttonSub.addActionListener(listener);
buttonMul.addActionListener(listener);
buttonDiv.addActionListener(listener);
buttonEqual.addActionListener(listener);
for(int i = 0 ; i <=9 ; i++){
button[i].addActionListener(listener);
}
for(int i = 0 ; i <=9 ; i++){
panelKeys_down.add(button[i]);
}
panelKeys_down.add(buttonAddSub);
panelKeys_down.add(buttonAdd);
panelKeys_down.add(buttonSub);
panelKeys_down.add(buttonMul);
panelKeys_down.add(buttonDiv);
panelKeys_down.add(buttonEqual);
panel.setLayout(new BorderLayout());
panel.add(textComputer,BorderLayout.NORTH);
panel.add(panelKeys_up,BorderLayout.CENTER);
panel.add(panelKeys_down,BorderLayout.SOUTH);
}
class ComputerActionListener implements ActionListener{
@Override
public void actionPerformed(ActionEvent event) {
// TODO Auto-generated method stub
Object keyButton = event.getSource();
String text = textComputer.getText();
DecimalFormat df = new DecimalFormat("0.###########");
//Backspace
if(keyButton == buttonBk && text.length() > 0){
textComputer.setText(text.substring(0,text.length()-1));
}
//C键
if(keyButton == buttonC){
result = 0;
textComputer.setText("");
}
//数字键
for(int i=0;i<10;i++){
if(keyButton == button[i]){
textComputer.setText(text+i);
}
}
if(keyButton == buttonAdd){
operator = 1;
}
if(keyButton == buttonSub){
operator = 2;
}
if(keyButton == buttonMul){
operator = 3;
}
if(keyButton == buttonDiv){
operator = 4;
}
//符号键
if(keyButton == buttonAdd || keyButton == buttonSub || keyButton == buttonMul || keyButton == buttonDiv || keyButton == buttonEqual){
switch(operator){
case ADD:
result += Double.parseDouble(text);
break;
case SUB:
result -=Double.parseDouble(text);
break;
case MUL:
result *=Double.parseDouble(text);
break;
case DIV:
result /=Double.parseDouble(text);
break;
default:
result = Double.parseDouble(text);
}
textComputer.setText("");
}
if(keyButton == buttonEqual){
textComputer.setText(String.valueOf(result));
}
}
}
public static void main(String args[]){
new Calculator();
}
}