JFrame doesn't display components

Question

I have problem with displaying components on my JFrame. I'm closing my current window and opening new one and want to display jLabel on it but nothing is happening. Code is below :

               Frame[] nF = DBChooser.getFrames(); 

                nF[0].setVisible(false);
                JFrame windoow = new JFrame("Processing");                       
                JPanel pan = new JPanel(); 
                windoow.setPreferredSize(new Dimension(400, 150));  
                pan.setPreferredSize(new Dimension(400, 150));                  

                JLabel textLabel = new JLabel ("Processing...");   
                textLabel.setLayout(null);
                pan.setLayout(null);
                windoow.setLayout(null);                   
                pan.add(textLabel);
                pan.revalidate();
                pan.repaint();                 
                windoow.getContentPane().add(pan); 
                windoow.setLocationRelativeTo(null);                    
                windoow.pack();                  
                windoow.setVisible(true);

I appreciate any help

1) Java GUIs have to work on different OS', screen size, screen resolution etc. using different PLAFs in different locales. As such, they are not conducive to pixel perfect layout. Instead use layout managers, or [combinations of them](http://stackoverflow.com/a/5630271/418556) along with layout padding and borders for [white space](http://stackoverflow.com/a/17874718/418556). 2) For better help sooner, post a [MCVE] or [Short, Self Contained, Correct Example](http://www.sscce.org/). 3) Provide ASCII art or a simple drawing of the *intended* layout of the GUI at minimum size, and .. — Andrew Thompson, Aug 22 '17 at 11:39

Krzysztof Cichocki · Answer 1 · 2017-08-22T10:21:32.447

1

It is because you set a null layout to window and panel without specifying any width, lenght or position, either use some LayoutManager or set these properties (eg. bounds). A null LayoutManager means that you need to set everything yourself, because there is nothing (no LayoutManager) that would place your elements automatically. This example uses a BorderLayout, which creates a nice effect:

the code:

import java.awt.BorderLayout;
import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Test {
    public static void main(String[] args) {
        JFrame windoow = new JFrame("Processing");
        JPanel pan = new JPanel();
        windoow.setPreferredSize(new Dimension(400, 150));
        pan.setPreferredSize(new Dimension(400, 150));

        JLabel textLabel = new JLabel("Processing...");
        textLabel.setLayout(null);
        pan.setLayout(new BorderLayout());
        windoow.setLayout(new BorderLayout());
        pan.add(textLabel);
        pan.revalidate();
        pan.repaint();
        windoow.getContentPane().add(pan);
        windoow.setLocationRelativeTo(null);
        windoow.pack();
        windoow.setVisible(true);
    }
}

edited Aug 22 '17 at 10:21

answered Aug 22 '17 at 09:30

Krzysztof Cichocki

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still the same, label isn't displaying – johansonik Aug 22 '17 at 09:39
@johansonik How can it be not displayed when i have run the same code, and I've post you the image of window with the message? – Krzysztof Cichocki Aug 22 '17 at 09:41
@johansonik Are you using exactly this code that I've posted in my answer? – Krzysztof Cichocki Aug 22 '17 at 10:05
Yes, exactly the same. – johansonik Aug 22 '17 at 10:17
@johansonik, please copy&paste this single class above and run it - it will show the exact window as the one I've posted. – Krzysztof Cichocki Aug 22 '17 at 10:22

score 1 · Answer 2 · answered Aug 22 '17 at 09:30

1

Why you need so many setLayout(null); ? I remove them and it worked

public class DBChooser extends Frame {

    public static void main(String args[]) {
        Frame[] nF = DBChooser.getFrames();
//      nF[0].setVisible(false);
        JFrame windoow = new JFrame("Processing");
        JPanel pan = new JPanel();
        windoow.setPreferredSize(new Dimension(400, 150));
        pan.setPreferredSize(new Dimension(400, 150));
        JLabel textLabel = new JLabel("Processing...");
//      textLabel.setLayout(null);
//      pan.setLayout(null);
//      windoow.setLayout(null);                   
        pan.add(textLabel);
        pan.revalidate();
        pan.repaint();
        windoow.getContentPane().add(pan);
        windoow.setLocationRelativeTo(null);
        windoow.pack();
        windoow.setVisible(true);
    }
}

answered Aug 22 '17 at 09:30

John Joe

12,412
16
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135

it didn't help, label isn't displaying – johansonik Aug 22 '17 at 09:42
It works fine in my pc. Maybe you need to post more code here – John Joe Aug 22 '17 at 09:43
What is `nF[0].setVisible(false);`? Are you sure your code can compile without commenting this ? – John Joe Aug 22 '17 at 09:47
Yes I'm sure it can. This nF[0] is the main window (frame) of my program but it works fine. – johansonik Aug 22 '17 at 09:52
please post the code that can compile by adding main function – John Joe Aug 22 '17 at 09:59

JFrame doesn't display components

2 Answers2