Question

java 编写的计算器如何支持键盘事件

源代码：

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

public class Calculator extends JFrame
{
public Calculator()
{
setTitle("计算器");
this.getContentPane().add(new CustomPanel().add(new CalculatorPanel()));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
}

class CalculatorPanel extends JPanel
{
private boolean start;
private String lastCommand;
private double result;
private JPanel panel;
private JLabel display;

public CalculatorPanel()
{
setLayout(new BorderLayout());
result = 0;
lastCommand = "=";
start = true;
display = new JLabel("0");
add(display, BorderLayout.NORTH);
ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();
// KeyListener keyListener = new MyKeyListener();
panel = new JPanel();
panel.setLayout(new GridLayout(4, 4));
addButton("7", insert);
addButton("8", insert);
addButton("9", insert);
addButton("/", command);

addButton("4", insert);
addButton("5", insert);
addButton("6", insert);
addButton("*", command);

addButton("1", insert);
addButton("2", insert);
addButton("3", insert);
addButton("-", command);

addButton("0", insert);
addButton(".", insert);
addButton("=", command);
addButton("+", command);

add(panel, BorderLayout.CENTER);
}
void addButton(String desp, ActionListener listener)
{
JButton btn = new JButton(desp);
btn.addActionListener(listener);
btn.addKeyListener(new MyKeyListener());
panel.add(btn);
}

class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String input = e.getActionCommand();
if (start)
{
display.setText("");
start = false;
}
display.setText(display.getText() + input);

}
}

class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String command = e.getActionCommand();
if (start)
{
if (command.equals("-"))
{
display.setText(command);
start = false;
}
else
lastCommand = command;
}
else
{
calculate(Double.parseDouble(display.getText()));
lastCommand = command;
start = true;
}
}

}

public class MyKeyListener extends KeyAdapter
{
public void keyPressed(KeyEvent evt)
{
String input = "";
String command = "";
}
}

public void calculate(double x)
{
if (lastCommand.equals("+")) result += x;
else if (lastCommand.equals("-")) result -= x;
else if (lastCommand.equals("*")) result *= x;
else if (lastCommand.equals("/")) result /= x;
else if (lastCommand.equals("=")) result = x;
display.setText("" + result);
}

}

请高手在clas MyKeyListener中的代码补充完整。谢谢！！！（限于字数，部分省略）。
public static void main(String[] agrs)
{
new Calculator().setVisible(true);
}
上次因为字数限制我没写main函数

Answer 1

char input =evt.getKeyChar();\\即可从键盘读入你按游漏下的字神迅烂符
然后用个变昌裤量把每个字符存起来 就行了

Answer 2

main函数在哪里
找不到入口阿