Tukukkk

In my application I have a list of 6 Jlabels, which are added to the contentPane in a for loop. After that I add 2 JButtons - one for removing all the labels and the second one for adding them again:

public class Test {



    private JFrame frame;



    public static void main(String args) {

        EventQueue.invokeLater(new Runnable() {

            public void run() {

                try {

                    Test window = new Test();

                    window.frame.setVisible(true);

                } catch (Exception e) {

                    e.printStackTrace();

                }

            }

        });

    }



    public Test() {

        initialize();

    }



    private void initialize() {

        frame = new JFrame();

        frame.setBounds(100, 100, 960, 620);

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setResizable(false);

        frame.setLocationRelativeTo(null);

        frame.getContentPane().setLayout(null);

        frame.getContentPane().setBackground(new Color(30, 30, 30));





        LinkedList<JLabel> labels = new LinkedList<>();

        for(int i = 0 ; i < 6 ; i++) {

            labels.get(i).setSize(280, 50);

            labels.setBackground(new Color(75, 75, 75));

            labels.setOpaque(true);

        }



        Button buttonAdd = new JButton("Add");

        buttonAdd.setBounds(310, 15, 150, 50);

        buttonAdd.addMouseListener(new MouseAdapter() {

            @Override

            public final void mouseClicked(MouseEvent event) {

                for(int i = 0 ; i < 6 ; i++) {

                    labels.get(i).setLocation(15, 15+50*i);

                    frame.getContentPane().add(labels.get(i));

                }

            }

        });



        Button buttonRemove = new JButton("Remove");

        buttonRemove.setBounds(310, 15, 150, 50);

        buttonRemove.addMouseListener(new MouseAdapter() {

            @Override

            public final void mouseClicked(MouseEvent event) {

                for(int i = 0 ; i < 6 ; i++) {

                    frame.getContentPane().remove(labels.get(i));

                }

            }

        });

    }

}

When I added the 6 labels outside of linsteners they were properly added to the ContentPane and displayed. Yet, when I try to do this via the buttons, upon clicking the buttonAdd nothing happens. They do not get displayed.

I tried messing with the hierarchy, setting the indices manually but nothing worked. I suspect the MouseListeners but I have no idea why this doesn't work.

First things first;

-Anything modifies the GUI has to be done in Event Dispatch Thread(EDT). You can read more why it is needed from this answer.

You have to call:

 Test.this.frame.revalidate();

 Test.this.frame.repaint();

Like below:

           for ( int i = 0; i < 6; i++ )

           {

              final JLabel l = labels.get( i );

                              l.setLocation( 15, 15 + (50 * i) );

              Test.this.frame.getContentPane().add( l );

           }

           Test.this.frame.revalidate();

           Test.this.frame.repaint();

Asides this I see in your code you use Button instead of JButton, I am assuming it is just a typing mistake. It should be JButton. Also

    for(int i = 0 ; i < 6 ; i++) {

    labels.get(i).setSize(280, 50);

    labels.setBackground(new Color(75, 75, 75));

    labels.setOpaque(true);

    }

this piece of code is just wrong, labels is a list not a JLabel. Define local variable

JLabel labelToAdd = labels.get(i)

labelToAdd.setSize(280, 50);

labelToAdd.setBackground(new Color(75, 75, 75));

labelToAdd.setOpaque(true);