Applet - Creating new objects from a Button Listener

[theneb]

Hello everyone, I'm attempting to create JComponents from when a
button is clicked. However I'm assuming I'm missing something? (Or
it's not possible)

This is some quick prototype code which shows my intentions.

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

public class myApplet extends Applet implements ActionListener{

private JPanel buttonPanel;
private HashMap<String,testButton> buttons;

private testButton myButton, secondButton, thirdButton;

public void init(){
buttonPanel = new JPanel();
buttons = new HashMap<String,testButton>();
buttons.put(String.valueOf(buttons.size()),new testButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
add(buttonPanel);
}//end init

public void start(){
System.out.println("START");
}

public void actionPerformed(ActionEvent event) {
System.out.println("Action");
}


private class testButton extends JButton implements ActionListener{


public testButton(){
setText("Button "+buttons.size());
addActionListener(this);
}

public void actionPerformed(ActionEvent event) {
System.out.println("Adding New Button");
buttons.put(String.valueOf(buttons.size()),new testButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
}

}

}//end myApplet


Example here: http://www.theneb.co.uk/applet-test/test.html

Cheers

 

[Tom Hawtin]

Hello everyone, I'm attempting to create JComponents from when a
button is clicked. However I'm assuming I'm missing something? (Or
it's not possible)

From the java.awt.Container.add API docs:

"Note: If a component has been added to a container that has been
displayed, validate must be called on that container to display the new
component. If multiple components are being added, you can improve
efficiency by calling validate only once, after all the components have
been added."

public class myApplet extends Applet implements ActionListener{

Much better to use anonymous inner classes for listeners, otherwise you
will have a mess. (And initial caps for type names.)

> private HashMap<String,testButton> buttons;

This can just be Map.

> buttons.put(String.valueOf(buttons.size()),new testButton());
> buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));

That's just confusing.

public void actionPerformed(ActionEvent event) {

Never used...

private class testButton extends JButton implements ActionListener{

Again, don't do listeners like that. And you don't need to extend
JButton at all.

public class MyApplet extends Applet {

private final Map<String,JButton> buttons =
new HashMap<String,JButton>();

private JPanel buttonPanel;

public void init() {
buttonPanel = new JPanel();
addButton();
}

private void addButton() {
String id = String.valueOf(buttons.size());
JButton button = new JButton(id);
button.addActionListener(new ActionListener {
public void actionPerformed(ActionEvent event) {
addButton();
}
});
buttons.put(id, button);
buttonPanel.add(button);
buttonPanel.validate();
}
}


(Disclaimer: Not compiled or tested.)

Tom Hawtin

 

[SadRed]

Hello everyone, I'm attempting to create JComponents from when a
button is clicked. However I'm assuming I'm missing something? (Or
it's not possible)

This is some quick prototype code which shows my intentions.

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

public class myApplet extends Applet implements ActionListener{

private JPanel buttonPanel;
private HashMap<String,testButton> buttons;

private testButton myButton, secondButton, thirdButton;

public void init(){
buttonPanel = new JPanel();
buttons = new HashMap<String,testButton>();
buttons.put(String.valueOf(buttons.size()),new testButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
add(buttonPanel);
}//end init

public void start(){
System.out.println("START");
}

public void actionPerformed(ActionEvent event) {
System.out.println("Action");
}

private class testButton extends JButton implements ActionListener{

public testButton(){
setText("Button "+buttons.size());
addActionListener(this);
}

public void actionPerformed(ActionEvent event) {
System.out.println("Adding New Button");
buttons.put(String.valueOf(buttons.size()),new testButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
}

}
}//end myApplet

Example here:http://www.theneb.co.uk/applet-test/test.html

Cheers

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

public class MyApplet extends JApplet{
private JPanel buttonPanel;
private HashMap<String,TestButton> buttons;
private TestButton myButton, secondButton, thirdButton;

public void init(){
buttonPanel = new JPanel();
buttons = new HashMap<String, TestButton>();
buttons.put(String.valueOf(buttons.size()), new TestButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
getContentPane().add(buttonPanel, BorderLayout.CENTER);
}//end init

private class TestButton extends JButton implements ActionListener{

public TestButton(){
setText("Button " + buttons.size());
addActionListener(this);
}

public void actionPerformed(ActionEvent event) {
System.out.println("Adding New Button");
buttons.put(String.valueOf(buttons.size()), new TestButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size() -
1)));
buttonPanel.revalidate();
}
}
}//end MyApplet

 

[Knute Johnson]

Hello everyone, I'm attempting to create JComponents from when a
button is clicked. However I'm assuming I'm missing something? (Or
it's not possible)

This is some quick prototype code which shows my intentions.

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

public class myApplet extends Applet implements ActionListener{

private JPanel buttonPanel;
private HashMap<String,testButton> buttons;

private testButton myButton, secondButton, thirdButton;

public void init(){
buttonPanel = new JPanel();
buttons = new HashMap<String,testButton>();
buttons.put(String.valueOf(buttons.size()),new testButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
add(buttonPanel);
}//end init

public void start(){
System.out.println("START");
}

public void actionPerformed(ActionEvent event) {
System.out.println("Action");
}


private class testButton extends JButton implements ActionListener{


public testButton(){
setText("Button "+buttons.size());
addActionListener(this);
}

public void actionPerformed(ActionEvent event) {
System.out.println("Adding New Button");
buttons.put(String.valueOf(buttons.size()),new testButton());
buttonPanel.add(buttons.get(String.valueOf(buttons.size()-1)));
}

}

}//end myApplet


Example here: http://www.theneb.co.uk/applet-test/test.html

Cheers

After you add or remove components from a container you need to call
validate() and usually repaint(). This will cause the LayoutManager to
re-layout your components. If your containers are JComponents (which
JApplet is not) you can call revalidate() on the container to have the
LayoutManager re-layout the component.

Also, you are using JButtons and an Applet. You should not mix AWT and
Swing components. If you are going to use JButtons, use a JApplet.

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

public class test extends JApplet {
public void init() {
setLayout(new FlowLayout());

JButton add = new JButton("Add a Button");
add.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
test.this.add(new Tutton("Press Me"));
test.this.validate();
test.this.repaint();
}
});
add(add);
}

class Tutton extends JButton implements ActionListener {
public Tutton(String text) {
super(text);
addActionListener(this);
}
public void actionPerformed(ActionEvent ae) {
test.this.remove((JComponent)ae.getSource());
test.this.validate();
test.this.repaint();
}
}
}

 

[theneb]

thenebwrote:














After you add or remove components from a container you need to call
validate() and usually repaint(). This will cause the LayoutManager to
re-layout your components. If your containers are JComponents (which
JApplet is not) you can call revalidate() on the container to have the
LayoutManager re-layout the component.

Also, you are using JButtons and an Applet. You should not mix AWT and
Swing components. If you are going to use JButtons, use a JApplet.

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

public class test extends JApplet {
public void init() {
setLayout(new FlowLayout());

JButton add = new JButton("Add a Button");
add.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
test.this.add(new Tutton("Press Me"));
test.this.validate();
test.this.repaint();
}
});
add(add);
}

class Tutton extends JButton implements ActionListener {
public Tutton(String text) {
super(text);
addActionListener(this);
}
public void actionPerformed(ActionEvent ae) {
test.this.remove((JComponent)ae.getSource());
test.this.validate();
test.this.repaint();
}
}

}

Appoligies for a late reply, thanks to all. My code now fully works.