Karan Nagpal Karan Nagpal - 2 months ago 28
Java Question

Java - setVisible(true)

I made a simple JDialog which contains a label and a button, its basically an equivalent of information dialog. So in the dialog, there is a method display() in which I called setVisible(true) five times.

From my knowledge, when this display method is called it should only display the dialog once but it actually created 5 dialogs, Why did it create 5 dialogs?

Edit1: My problem is more similar to this :

import java.awt.event.*;import java.awt.*;import javax.swing.*;
class Demo implements ActionListener
{
JFrame f;
JButton b;
DisplayDialog dialog;
public Demo()
{
f = new JFrame();
f.setSize(200,200);

b = new JButton("Click me");

f.add(b);
dialog = new DisplayDialog();

b.addActionListener(this);
f.setVisible(true);
}

public void actionPerformed(ActionEvent e)
{
Object o = e.getSource();

if(o==b)
{
dialog.display("Hello");
dialog.display("Hello");
dialog.display("Hello");
dialog.display("Hello");
dialog.display("Hello5");
}
}

public static void main(String args[])
{
Demo d = new Demo();
}

class DisplayDialog implements ActionListener
{
JDialog dg;
JLabel l;
JButton b;
Font myfont;

public DisplayDialog()
{
dg = new JDialog(f,"Alert!",true);
dg.setSize(300,150);
l = new JLabel("Message");
b = new JButton("OK");

myfont = new Font("Serif",Font.BOLD,12);
l.setFont(myfont);

dg.add(l);
dg.add(b,"South");

dg.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);

b.addActionListener(this);
}

public void actionPerformed(ActionEvent e)
{
Object o = e.getSource();
if(o==b)
{
dg.setVisible(false);
}
}

public void display(String str)
{
l.setText(str);
dg.setVisible(true);

}
}
}


Edit2 : Now a situation like this is occurring in my program and rather than displaying the dialog 5 times, I want it to display the last one, what can i do to achieve this?

Answer

Ok so basicly it is not showing 5 times at once only it is shown 5 times in a row.

JDialog.setVisible(true) is a blocking operation and blocks until dialog is closed.

So one dialog pops up and app blocks on setVisible(true) when you close it, another serVisible(true) is invoked and so on.