我用JAVA编的一个计算器

界面有点像WIN XP带的简单计算器，但只能实现一些简单的功能，目前还没实现键盘输入。由于是初学JAVA,程序可能不会完美，希望大家不吝赐教，大家多多交流。
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.Toolkit;
import java.awt.Dimension;
public class Calculator extends JFrame implements ActionListener{
private final String[] BUTTON_WEST = { " ", "MC", "MR", "MS", "M+" };
private final String[] BUTTON_NORTH = { "Backspace", "CE", "C" };
private final String[] BUTTON_CENTER = { "7", "8", "9", "/", "sqrt", "4", "5", "6",
"*", "%", "1", "2", "3", "-", "1/x", "0", "+/-", ".", "+", "=" };
private JButton[] button_west = new JButton[BUTTON_WEST.length];
private JButton[] button_north = new JButton[BUTTON_NORTH.length];
private JButton[] button_center = new JButton[BUTTON_CENTER.length];
private JTextField text = new JTextField("0");

private boolean firstButton = true;
private double resultNum = 0.0;
private String operator = "=";
private boolean operateValidFlag = true;

Calculator(){
super();
init();
this.setBackground(Color.LIGHT_GRAY);
this.setTitle("计算器");
this.setResizable(false);
this.pack();

}

void init(){
text.setHorizontalAlignment(JTextField.RIGHT);
text.setEditable(false);
text.setBackground(Color.WHITE);

JPanel button_west_panel = new JPanel();
button_west_panel.setLayout(new GridLayout(5,1,3,3));
for(int i=0;i<BUTTON_WEST.length;i++){
button_west[i] = new JButton(BUTTON_WEST[i]);
button_west_panel.add(button_west[i]);
button_west[i].setForeground(Color.RED);

}

JPanel button_north_panel = new JPanel();
button_north_panel.setLayout(new GridLayout(1,3,3,3));
for(int i=0;i<BUTTON_NORTH.length;i++){
button_north[i] = new JButton(BUTTON_NORTH[i]);
button_north_panel.add(button_north[i]);
button_north[i].setForeground(Color.RED);
}

JPanel button_center_panel = new JPanel();
button_center_panel.setLayout(new GridLayout(4,5,3,3));
for(int i=0;i<BUTTON_CENTER.length;i++){
button_center[i] = new JButton(BUTTON_CENTER[i]);
button_center_panel.add(button_center[i]);
button_center[i].setForeground(Color.BLUE);

}
button_center[3].setForeground(Color.RED);
button_center[8].setForeground(Color.RED);
button_center[13].setForeground(Color.RED);
button_center[18].setForeground(Color.RED);
button_center[19].setForeground(Color.RED);

JPanel panel1 = new JPanel();
panel1.setLayout(new BorderLayout(3,3));
panel1.add("North",button_north_panel);
panel1.add("Center",button_center_panel);

JPanel panel2 = new JPanel();
panel2.setLayout(new BorderLayout());
panel2.add("Center",text);

this.getContentPane().setLayout(new BorderLayout(3,5));
this.getContentPane().add("North",panel2);
this.getContentPane().add("West",button_west_panel);
this.getContentPane().add("Center",panel1);

for(int i=0;i<BUTTON_WEST.length;i++){
button_west[i].addActionListener(this);

}

for(int i=0;i<BUTTON_NORTH.length;i++){
button_north[i].addActionListener(this);

}

for(int i=0;i<BUTTON_CENTER.length;i++){
button_center[i].addActionListener(this);

}
}

public void actionPerformed(ActionEvent e){
String button = e.getActionCommand();
if(button.equals(button_north[0])){
handleBackspace();
}else if(button.equals(button_north[1])){
text.setText("0");
}else if(button.equals(button_north[2])){
handleC();
}else if("0123456789.".indexOf(button) >= 0){
handleNumber(button);
}else{
handleOperator(button);
}

}

private void handleBackspace(){
String getText = text.getText();
if(getText.length()>0){
getText = getText.substring(0,getText.length()-1);
if(getText.length()==0){
text.setText("0");
firstButton = true;
operator = "=";
}else{
text.setText(getText);
}
}
}

private void handleC(){
text.setText("0");
firstButton = true;
operator = "=";
}

private void handleNumber(String button){
System.out.println(resultNum);
if(firstButton){
text.setText(button);
}else if ((button.equals(".")) && (text.getText().indexOf(".") < 0)){
text.setText(text.getText() + ".");
} else if (!button.equals(".")) {
text.setText(text.getText() + button);
}
firstButton = false;
}

private void handleOperator(String button){
System.out.println(operator);

if (operator.equals("/")) {
if (getNumberFromText() == 0.0){
operateValidFlag = false;
text.setText("除数不能为零");
} else {
resultNum /= getNumberFromText();
}
} else if (operator.equals("1/x")) {
if (resultNum == 0.0){
operateValidFlag = false;
text.setText("零没有倒数");
} else {
resultNum = 1 / resultNum;
}
} else if (operator.equals("+")){
resultNum += getNumberFromText();
} else if (operator.equals("-")){
resultNum -= getNumberFromText();
} else if (operator.equals("*")){
resultNum *= getNumberFromText();
} else if (operator.equals("sqrt")) {
resultNum = Math.sqrt(resultNum);
} else if (operator.equals("%")){
resultNum = resultNum / 100;
} else if (operator.equals("+/-")){
resultNum = resultNum * (-1);
} else if (operator.equals("=")){
resultNum = getNumberFromText();
}
if (operateValidFlag) {
long t1;
double t2;
t1 = (long) resultNum;
t2 = resultNum - t1;
if (t2 == 0) {
text.setText(String.valueOf(t1));
} else {
text.setText(String.valueOf(resultNum));
}
}
operator = button;
System.out.println(operator);
System.out.println(resultNum);
firstButton = true;
operateValidFlag = true;
}

private double getNumberFromText() {
double result = 0;
try {
result = Double.valueOf(text.getText()).doubleValue();
} catch (NumberFormatException e){
}
return result;
}

public static void main(String args[]) {
Calculator calculator1 = new Calculator();
Dimension d1=Toolkit.getDefaultToolkit().getScreenSize();
Dimension d2=calculator1.getSize();
calculator1.setLocation((d1.width-d2.width)/2,(d1.height-d2.height)/2);
calculator1.setVisible(true);
calculator1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}本文出自 “伯爵” 博客，请务必保留此出处http://bojue.blog.51cto.com/200836/47047