KeyListener - Demo
This program shows how to implement KeyListener. A form with a textfield and a button is created. As user types @ or # in the textfield "Oki Good!!!" message is displayed in a message box otherwise "This is not @ or #" message is displayed. In this program, user if types @ or # at the beginning, "This is not @ or #" message is displayed. Why? Figure it out
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.security.Key;
public class KeyExample extends JFrame implements KeyListener {
JTextField txt;
JButton btn;
public KeyExample(){
txt = new JTextField(20);
txt.setToolTipText("Enter Character @ or #");
txt.addKeyListener(this);
txt.setBounds(20,20,100,22);
btn = new JButton("Check");
btn.setToolTipText("Click to submit");
btn.setBounds(20,50,100,22);
add(txt);
add(btn);
setLayout(null);
setVisible(true);
setTitle("KeyListener");
setSize(400,400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
}
public void keyTyped(KeyEvent e) {
String str = txt.getText();
if(!str.contains("@") && !str.contains("#")){
JOptionPane.showMessageDialog(this,"This is not @ or #");
}else
JOptionPane.showMessageDialog(this,"Oki Good!!!");
btn.setText("TYPED " + e.getKeyChar());
}
public void keyPressed(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
}
public static void main(String[] args) {
new KeyExample();
}
}
