Question

用JAVA编写计算器，要有+，-，*，/，CE，BackSpace键

用JAVA编写计算器，只需要有+，-，*，/，=，CE，BackSpace功能

Answer 1

package com.xuzs.test;

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

public class Calculator extends JFrame implements ActionListener {

private static final long serialVersionUID = 1L;
private JTextField txtResult;
private JButton btnZero, btnOne, btnTwo, btnThree, btnFour, btnFive,
btnSix, btnSeven, btnEight, btnNine, btnPlus, btnMinus, btnTimes,
btnDivided, btnEqual, btnPoint, btnC, btnCE, btnSqrt, btnPlusMinus;
int z;
double x, y;
StringBuffer str;

public Calculator() {
super("计算器");
this.setSize(311, 231);
this.setLocation(300, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

this.setLayout(new GridLayout(1, 1));// 网格布局
JPanel panel = new JPanel(new GridLayout(6, 1));// 面板 网格布局6行1列
this.add(panel);

txtResult = new JTextField("0");
Color BackColor = new Color(255, 255, 255);
Color ForeColor = new Color(0, 0, 0);
txtResult.setBackground(BackColor);
txtResult.setForeground(ForeColor);

panel.add(txtResult);
txtResult.setHorizontalAlignment(JTextField.RIGHT);
txtResult.setEnabled(false);
// text.setEnabled(true);

JPanel panel_1 = new JPanel(new GridLayout(1, 4));
panel.add(panel_1);

btnSqrt = new JButton("sqrt");
panel_1.add(btnSqrt);
btnSqrt.addActionListener(this);
btnPlusMinus = new JButton("+/-");
panel_1.add(btnPlusMinus);
btnPlusMinus.addActionListener(this);
btnCE = new JButton("CE");
panel_1.add(btnCE);
btnCE.addActionListener(this);
btnC = new JButton("C");
panel_1.add(btnC);
btnC.addActionListener(this);

JPanel panel_2 = new JPanel(new GridLayout(1, 4));
panel.add(panel_2);

btnSeven = new JButton("7");
panel_2.add(btnSeven);
btnSeven.addActionListener(this);
btnEight = new JButton("8");
panel_2.add(btnEight);
btnEight.addActionListener(this);
btnNine = new JButton("9");
panel_2.add(btnNine);
btnNine.addActionListener(this);
btnDivided = new JButton("/");
panel_2.add(btnDivided);
btnDivided.addActionListener(this);

JPanel panel_3 = new JPanel(new GridLayout(1, 4));
panel.add(panel_3);

btnFour = new JButton("4");
panel_3.add(btnFour);
btnFour.addActionListener(this);
btnFive = new JButton("5");
panel_3.add(btnFive);
btnFive.addActionListener(this);
btnSix = new JButton("6");
panel_3.add(btnSix);
btnSix.addActionListener(this);
btnTimes = new JButton("*");
panel_3.add(btnTimes);
btnTimes.addActionListener(this);

JPanel panel_4 = new JPanel(new GridLayout(1, 4));
panel.add(panel_4);

btnOne = new JButton("1");
panel_4.add(btnOne);
btnOne.addActionListener(this);
btnTwo = new JButton("2");
panel_4.add(btnTwo);
btnTwo.addActionListener(this);
btnThree = new JButton("3");
panel_4.add(btnThree);
btnThree.addActionListener(this);
btnMinus = new JButton("-");
panel_4.add(btnMinus);
btnMinus.addActionListener(this);

JPanel panel_5 = new JPanel(new GridLayout(1, 4));
panel.add(panel_5);

btnZero = new JButton("0");
panel_5.add(btnZero);
btnZero.addActionListener(this);
btnPoint = new JButton(".");
panel_5.add(btnPoint);
btnPoint.addActionListener(this);
btnEqual = new JButton("=");
panel_5.add(btnEqual);
btnEqual.addActionListener(this);
btnPlus = new JButton("+");
panel_5.add(btnPlus);
btnPlus.addActionListener(this);

str = new StringBuffer();

this.setVisible(true);

}

public void windowClosing(WindowEvent a) {
System.exit(0);
}

public void actionPerformed(ActionEvent e) {

try {
if (e.getSource() == btnC) {
txtResult.setText("0");
str.setLength(0);
} else if (e.getSource() == btnCE) {
txtResult.setText("0.");
str.setLength(0);
} else if (e.getSource() == btnPlusMinus) {
x = Double.parseDouble(txtResult.getText().trim());
txtResult.setText("" + (-x));
}

else if (e.getSource() == btnPlus) {
x = Double.parseDouble(txtResult.getText().trim());
str.setLength(0);
y = 0d;
z = 1;
} else if (e.getSource() == btnMinus) {
x = Double.parseDouble(txtResult.getText().trim());
str.setLength(0);
y = 0d;
z = 2;
} else if (e.getSource() == btnTimes) {
x = Double.parseDouble(txtResult.getText().trim());
str.setLength(0);
y = 0d;
z = 3;
} else if (e.getSource() == btnDivided) {
x = Double.parseDouble(txtResult.getText().trim());
str.setLength(0);
y = 0d;
z = 4;
} else if (e.getSource() == btnEqual) {
str.setLength(0);
switch (z) {
case 1:
txtResult.setText("" + (x + y));
break;
case 2:
txtResult.setText("" + (x - y));
break;
case 3:
txtResult.setText("" + (x * y));
break;
case 4:
txtResult.setText("" + (x / y));
break;
}
}

else if (e.getSource() == btnPoint) {
if (txtResult.getText().trim().indexOf('.') != -1)// 判断字符串中是否已经包含了小数点
{

} else// 如果没数点有小
{
if (txtResult.getText().trim().equals("0"))// 如果初时显示为0
{
str.setLength(0);
txtResult.setText((str.append("0"
+ e.getActionCommand())).toString());
} else if (txtResult.getText().trim().equals(""))// 如果初时显示为空则不做任何操作
{
} else {
txtResult.setText(str.append(e.getActionCommand())
.toString());
}
}

y = 0d;
}

else if (e.getSource() == btnSqrt)// 求平方根
{
x = Double.parseDouble(txtResult.getText().trim());
txtResult.setText("数字格式异常");
if (x < 0)
txtResult.setText("负数没有平方根");
else
txtResult.setText("" + Math.sqrt(x));
str.setLength(0);
y = 0d;
}

else if (e.getSource() == btnZero)// 如果选择的是"0"这个数字键
{
if (txtResult.getText().trim().equals("0"))// 如果显示屏显示的为零不做操作
{
} else {
txtResult.setText(str.append(e.getActionCommand())
.toString());
y = Double.parseDouble(txtResult.getText().trim());
}
}

else// 其他的数字键
{
txtResult.setText(str.append(e.getActionCommand()).toString());
y = Double.parseDouble(txtResult.getText().trim());
}
} catch (NumberFormatException ae) {
txtResult.setText("数字格式异常");
} catch (StringIndexOutOfBoundsException ae) {
txtResult.setText("字符串索引越界");
}

}

public static void main(String arg[]) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception e) {
e.printStackTrace();
}
new Calculator();
}

}