Frame not becoming invisible

[sbjibo]

Here is a code I made to practice how to make JFrame and add components to it.
But the problem is:
1. On line 8, shouldn't the frame turn invisible?
2. On line 7, shouldn't the frame be in the center of the screen?

Could anyone help?
P.S : I did it in Ready to Program (if thats the source of any problem)

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JButtonDemo2 {
        public static void main(String[] args) {
                mkay app = new mkay();
                app.setLocationRelativeTo(null);
                app.setVisible(false);
        }
}
class mkay extends javax.swing.JFrame{        
        public mkay() {
            init();
        }
        JFrame jtfMainFrame;
        JButton jbnButton1, jbnButton2;
        JTextField jtfInput;
        JPanel jplPanel;
        public void init() {
                jtfMainFrame = new JFrame("Which Button Demo");
                jtfMainFrame.setSize(50, 50);
                jbnButton1 = new JButton("Button 1");
                jbnButton2 = new JButton("Button 2");
                jtfInput = new JTextField(20);
                jplPanel = new JPanel();
                jbnButton1.addActionListener(new ActionListener() {
 
                        public void actionPerformed(ActionEvent e) {
                                jtfInput.setText("Button 1!");
                                mkay app2 = new mkay();
                                app2.setLocationRelativeTo(null);
                        }
                });
                jbnButton2.addActionListener(new ActionListener() {
 
                        public void actionPerformed(ActionEvent e) {
                                jtfInput.setText("Button 2!");
                        }
                });
                jplPanel.setLayout(new FlowLayout());
                jplPanel.add(jtfInput);
                jplPanel.add(jbnButton1);
                jplPanel.add(jbnButton2);
                jtfMainFrame.getContentPane().add(jplPanel, BorderLayout.CENTER);
                jtfMainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                jtfMainFrame.pack();
                jtfMainFrame.setVisible(true);
        }
}

[Norm]

What happens when you execute the program?

[sbjibo]

When you execute the program, a frame with a text field, and 2 buttons labeled button1 and button 2.
But the program is not supposed to show anything

[Norm]

Try changing the setVisible parameter to true and see what happens.

[sbjibo]

When you write app.setVisible(true), it creates a new window, but it has no components. its just an empty frame.

[sbjibo]

Does the fact that I made it in 'Ready To Program' matter ? because my friend made a code simililar to this in netbeans, and it worked.

[Norm]

The IDE should not make any difference. Your friend's code must have been different.

Did you see two windows after the change I suggested?
Look at the code. There are two JFrame objects being created.

[sbjibo]

I dont understand why two windows are created. When I say 'mkay app = new mkay(), that should make a window. So where is the other window coming from?

[Norm]

What title is shown in the window with the components? Do a Find in the source for that String to see where it is used. Or look for a statement that has: new JFrame(

[sbjibo]

It is created at line 20 of my program. The title of the window is "Which button Demo"

[Norm]

Do you now see where there are two windows being created?

[sbjibo]

I think thats the only line where the window is created. Could you tell me where is the other window being created?

[sbjibo]

Wait, the mkay class extends the JFrame, so that s the other wiindow, right?

The code works if you dont create another frame inside the mkay class.



--Thanks for helping me

[Norm]

Right.
One was mkay that extends JFrame

The other was:
JFrame jtfMainFrame;
...
jtfMainFrame = new JFrame("Which Button Demo");

[Karthik Prabhu]

See,2 frames are being created because u have created 2 objects-app and jftMainFrame