Java adds code instances of four methods for event listening
- 2020-04-01 03:27:39
- OfStack
Several ways to add events in Java (reprinted from codebrother's article with minor changes) :
class EventListener1 extends JFrame implements ActionListener {
private JButton btBlue, btDialog;
public EventListener1() {
setTitle("Java GUI Event monitoring processing ");
setBounds(100, 100, 500, 350);
setLayout(new FlowLayout());
btBlue = new JButton(" blue ");
btDialog = new JButton(" Popup window ");
//Adds an event listener to the button
btBlue.addActionListener(this);
btDialog.addActionListener(this);
add(btBlue);
add(btDialog);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
//* * * * * * * * * * * * * * * * * * * * * * * * * * * event handling * * * * * * * * * * * * * * * * * * * * * * * * * * *
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == btBlue) {
Container c = getContentPane();
c.setBackground(Color.BLUE);
}
else if (e.getSource() == btDialog) {
JDialog dialog = new JDialog();
dialog.setBounds(300, 200, 400, 300);
dialog.setVisible(true);
}
}
}
class EventListener3 extends JFrame {
private JButton btBlue, btDialog;
//A constructor
public EventListener3() {
setTitle("Java GUI Event monitoring processing ");
setBounds(100, 100, 500, 350);
setLayout(new FlowLayout());
btBlue = new JButton(" blue ");
btDialog = new JButton(" Popup window ");
//Adding an event listener object (object-oriented idea)
btBlue.addActionListener(new ColorEventListener());
btDialog.addActionListener(new DialogEventListener());
add(btBlue);
add(btDialog);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
//The inner class ColorEventListener implements the ActionListener interface
class ColorEventListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
Container c = getContentPane();
c.setBackground(Color.BLUE);
}
}
//The inner class DialogEventListener implements the ActionListener interface
class DialogEventListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
JDialog dialog = new JDialog();
dialog.setBounds(300, 200, 400, 300);
dialog.setVisible(true);
}
}
}
class EventListener2 extends JFrame {
private JButton btBlue, btDialog;
public EventListener2() {
setTitle("Java GUI Event monitoring processing ");
setBounds(100, 100, 500, 350);
setLayout(new FlowLayout());
btBlue = new JButton(" blue ");
btDialog = new JButton(" Popup window ");
//Add an event listener (anonymous class here)
btBlue.addActionListener(new ActionListener() {
//The event processing
@Override
public void actionPerformed(ActionEvent e) {
Container c = getContentPane();
c.setBackground(Color.BLUE);
}
});
//And add an event listener
btDialog.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JDialog dialog = new JDialog();
dialog.setBounds(300, 200, 400, 300);
dialog.setVisible(true);
}
});
add(btBlue);
add(btDialog);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
class EventListener4 extends JFrame {
private JButton btBlue, btDialog;
public EventListener4() {
setTitle("Java GUI Event monitoring processing ");
setBounds(100, 100, 500, 350);
setLayout(new FlowLayout());
btBlue = new JButton(" blue ");
btDialog = new JButton(" Popup window ");
//Adds an event listener to the button
btBlue.addActionListener(new ColorEventListener(this));
btDialog.addActionListener(new DialogEventListener());
add(btBlue);
add(btDialog);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
//The external class ColorEventListener implements the ActionListener interface
class ColorEventListener implements ActionListener {
private EventListener4 el;
ColorEventListener(EventListener4 el) {
this.el = el;
}
@Override
public void actionPerformed(ActionEvent e) {
Container c = el.getContentPane();
c.setBackground(Color.BLUE);
}
}
//The external DialogEventListener class implements the ActionListener interface
class DialogEventListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
JDialog dialog = new JDialog();
dialog.setBounds(300, 200, 400, 300);
dialog.setVisible(true);
}
}
public class ActionListenerTest
{
public static void main(String args[])
{
new EventListener2();
}
}