LAB ACTIVITY 3J

Learning Outcomes

  By the end of this lab, students should be able to :

• • Write Java programs using Event Handling

  • Write Java programs using Event Handling with GUI Components

Hardware/ Software : Personal Computer, Java Development Kit version X.x.x., NetBeans IDE 12.0

LAB ACTIVITY 3J

Activity Outcome: Student know how to create event handling program for KeyEvent.

CREATE New Project name as KeyDemo

i. Type the following code:

package keydemo;

import java.awt.*;

import javax.swing.*;

public class KeyDemo extends JFrame{

private String line1 = "", line2 = "", line3 = "";

private JTextArea textArea;

    public KeyDemo()

    {

        super("Demonstrating Keystroke Events");

        textArea = new JTextArea(10, 15);

        textArea.setText("Press any key on the keyboard...");

        textArea.setEnabled(false);

        textArea.setDisabledTextColor(Color.BLACK);

        getContentPane().add(textArea);

        setSize(400, 100);

        setVisible(true);

    }

    public static void main(String args[]){

        KeyDemo application = new KeyDemo();

        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

}   

ii. Declaration of the event handler class

a) Add package java.awt.event.*;  

b) implements KeyListener

     c) addKeyListener(this);

example image:

iii. Create event for KeyEvent

    public void keyPressed(KeyEvent event)

    {

        line1 = "Key pressed: " + event.getKeyText(event.getKeyCode());

        setLines2and3(event);

    }

    public void keyReleased(KeyEvent event)

    {

        line1 = "Key released: " + event.getKeyText(event.getKeyCode());

        setLines2and3(event);

    }

    public void keyTyped(KeyEvent event)

    {

        line1 = "Key typed: " + event.getKeyText(event.getKeyCode());

        setLines2and3(event);

    }

    private void setLines2and3(KeyEvent event)

    {

        line2 = "This key is " + (event.isActionKey() ? "" : "not" ) + "an action key";

        String temp =  event.getKeyModifiersText(event.getModifiers() );

        line3 = "Modifiers key pressed: " + (temp.equals( "" ) ? "none" : temp);

        textArea.setText(line1 + "\n" + line2 + "\n" + line3 + "\n" );

    }

example image:

FULL CODE & EXAMPLE GUI OUTPUT :

package keydemo;

import java.awt.*;

import javax.swing.*;

import java.awt.event.*;

public class KeyDemo extends JFrame implements KeyListener{

private String line1 = "", line2 = "", line3 = "";

private JTextArea textArea;

    public KeyDemo()

    {

        super("Demonstrating Keystroke Events");

        textArea = new JTextArea(10, 15);

        textArea.setText("Press any key on the keyboard...");

        textArea.setEnabled(false);

        textArea.setDisabledTextColor(Color.BLACK);

        getContentPane().add(textArea);

addKeyListener(this);

        setSize(400, 100);

        setVisible(true);

    }

    public void keyPressed(KeyEvent event)

    {

        line1 = "Key pressed: " + event.getKeyText(event.getKeyCode());

        setLines2and3(event);

    }

    public void keyReleased(KeyEvent event)

    {

        line1 = "Key released: " + event.getKeyText(event.getKeyCode());

        setLines2and3(event);

    }

    public void keyTyped(KeyEvent event)

    {

        line1 = "Key typed: " + event.getKeyText(event.getKeyCode());

        setLines2and3(event);

    }

    private void setLines2and3(KeyEvent event)

    {

        line2 = "This key is " + (event.isActionKey() ? "" : "not" ) + "an action key";

        String temp =  event.getKeyModifiersText(event.getModifiers() );

        line3 = "Modifiers key pressed: " + (temp.equals( "" ) ? "none" : temp);

        textArea.setText(line1 + "\n" + line2 + "\n" + line3 + "\n" );

    }

    public static void main(String args[]){

        KeyDemo application = new KeyDemo();

        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

}   

OUTPUT :   (Type any key on your KeyBoard to show an output at TextArea)