Please add keyboard focus events to swing calculator. Its very argent.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
A frame with a calculator panel.
*/
class CalculatorFrame1 extends JFrame
{
private static final long serialVersionUID=0;
public CalculatorFrame1()
{
setTitle("Calculator");
Container contentPane = getContentPane();
CalculatorPanel panel = new CalculatorPanel();
contentPane.add(panel);
pack();
setVisible(true);
}
public static void main(String[] args)
{
CalculatorFrame1 frame = new CalculatorFrame1();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//frame.show();
}
}
/**
A panel with calculator buttons and a result display.
*/
class CalculatorPanel extends JPanel implements KeyListener
{
private static final long serialVersionUID=0;
private JTextField display;
private JPanel panel;
private double result;
private String lastCommand;
private boolean start;
public CalculatorPanel()
{
setLayout(new BorderLayout());
result = 0;
lastCommand = "=";
start = true;
// add the display
display = new JTextField("");
// display.addKeyListener(this);
// display.addKeyListener(this);
add(display, BorderLayout.NORTH);
display.setFocusable(true);
ActionListener insert = new InsertAction();
ActionListener command = new CommandAction();
// add the buttons in a 4 x 4 grid
panel = new JPanel();
panel.setLayout(new GridLayout(5, 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);
addButton("Clear", command);
add(panel, BorderLayout.CENTER);
//this.addKeyListener(this);
}
/**
Adds a button to the center panel.
@param label the button label
@param listener the button listener
*/
private void addButton(String label, ActionListener listener)
{
JButton button = new JButton(label);
button.addActionListener(listener);
panel.add(button);
}
/**
This action inserts the button action string to the
end of the display text.
*/
private class InsertAction implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
String input = event.getActionCommand();
if (start)
{
display.setText("");
start = false;
}
display.setText(display.getText() + input);
}
}
/**
This action executes the command that the button
action string denotes.
*/
private class CommandAction implements ActionListener
{
public void actionPerformed(ActionEvent evt)
{
String command = evt.getActionCommand();
// System.out.println("The value clear"+command);
if (command.equals("Clear"))
{
display.setText("");
start = false;
}
else
{
if (start)
{
if (command.equals("-"))
{
display.setText(command);
start = false;
}
else
lastCommand = command;
}
else
{
calculate(Double.parseDouble(display.getText()));
lastCommand = command;
start = true;
}
}
}
}
/**
Carries out the pending calculation.
@param x the value to be accumulated with the prior result.
*/
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);
}
public void keyTyped(KeyEvent e) {
//You should only rely on the key char if the event
//is a key typed event.
int id = e.getID();
String keyString="";
System.out.println("The value KeyEvent.KEY_TYPED"+KeyEvent.KEY_TYPED);
if (id == KeyEvent.KEY_TYPED) {
char c = e.getKeyChar();
//System.out.println("The value c"+c);
if(c=='*' || c=='/' || c=='-'||c=='+' || c=='=')
{
start = true;
}
else
{
start = false;
keyString = display.getText()+ c ;
System.out.println("The value keyString"+keyString);
}
}
else {
calculate(Double.parseDouble(display.getText()));
start = true;
}
display.setText(keyString);
}
public void keyPressed(KeyEvent e) {
//You should only rely on the key char if the event
//is a key typed event.
/**
String keyString;
int id = e.getID();
if (id == KeyEvent.KEY_TYPED) {
char c = e.getKeyChar();
keyString = "key character = '" + c + "'";
} else {
int keyCode = e.getKeyCode();
keyString = "key code = " + keyCode
+ " ("
+ KeyEvent.getKeyText(keyCode)
+ ")";
}
display.setText("keyPressed:::"+keyString);**/
}
public void keyReleased(KeyEvent e) {
//You should only rely on the key char if the event
//is a key typed event.
/**
String keyString;
int id = e.getID();
if (id == KeyEvent.KEY_TYPED) {
char c = e.getKeyChar();
keyString = "key character = '" + c + "'";
} else {
int keyCode = e.getKeyCode();
keyString = "key code = " + keyCode
+ " ("
+ KeyEvent.getKeyText(keyCode)
+ ")";
}
display.setText("keyReleased:::"+keyString);**/
}
}
