Remove component from JFrame with absolute layout

Question

I have a JFrame and JPanel inside the JFrame with absolute layout. I wanted to have a button when clicked the JPanel will be removed. I called jFrame.remove(jPanel);
jFrame.repaint();
jFrame.validate();
I can't call jFrame.revalidate(), since JFrame doesn't provide revalidate() method. I try everything, but I can't get that JPanel removed. Could somebody help me please. Oh I tried jPanel.setBounds( 0,0,0,0); and the jPanel is disappeared, but I don't think this is the right solution. Is my problem with the absolute layout?
Thanks

Answer 1

public class MainGame
     public void game()
          GridBagLayout gridBagLayout = new GridBagLayout();
          GridBagConstraints constraints = new GridBagConstraints();
          final MainFrame mainFrame = new MainFrame();
          mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          mainFrame.setLayout( gridBagLayout );
          JPanel mainGamePanel = new JPanel();
          mainGamePanel.setLayout( new BorderLayout() );
          mainGamePanel.setBackground( Color.black );
          final Room mainEntrance = new Room( "at the main entrance of the deep forest" );
          mainEntrance.setBackground( Color.white );
          mainEntrance.setLayout( null );
          mainEntrance.setExit( Direction.UP, null );
          mainGamePanel.add( mainEntrance, BorderLayout.CENTER );
//          c.fill = GridBagConstraints.CENTER;
          constraints.ipady = 800;      //make this component tall
          constraints.ipadx = 600;
          constraints.anchor = GridBagConstraints.WEST;
          constraints.gridx = 0;
          constraints.gridy = 0;
          gridBagLayout.setConstraints( mainGamePanel, constraints );
          mainFrame.getContentPane().add( mainGamePanel );
          thePlayer = new Human( "Cloud" , "The player" );
          thePlayer.setMaximumWeight( MAXIMUM_WEIGHT );
          thePlayer.setImage( Constants.CHARACTER_FRONT );
          thePlayer.setBounds(0 , 0, 40, 30 );
          thePlayer.setBorder( BorderFactory.createLineBorder( Color.black ) );
          mainEntrance.add( thePlayer );
          apple = new EdibleItem( "apple" , "Give more 10 HP" );
          apple.setHp( 100 );
          apple.setImage( Constants.APPLE );
          apple.setBounds( 40, 0, 40, 30 );
          apple.setBorder( BorderFactory.createLineBorder( Color.black ) );
          mainEntrance.add( apple );
          thePlayer.addItem( apple );
          apple1 = new JPanelWithBackground();
          apple1.setImage( Constants.APPLE );
          apple1.setBounds( 80, 60, 40, 30 );
          apple1.setBorder( BorderFactory.createLineBorder( Color.black ) );
          mainEntrance.add( apple1 );
//          final Room forest = new Room( "at the main entrance of the deep forest" );
//          forest.setBounds( 0, 0, 800, 600 );
//          forest.setBackground( Color.white );
//          forest.setLayout( null );
//          forest.setExit( Direction.UP, null );
//          // Add to list
          listOfItems.add( apple );
          listOfItems.add( apple1 );
           * Main Control Panel to control character and actions
          JPanel controlPanel = new JPanel();
          controlPanel.setBackground( Color.black );
          controlPanel.setBounds( 1000, 0, 600, 600 );
          controlPanel.setLayout( new GridLayout( 0, 1 ) );
          JButton eatButton = new JButton( "EAT" );
          // Set this button to setFocusable(false) to prevent this button being focused
          // So the focus will stay at JFrame
          eatButton.setFocusable( false );
          eatButton.addActionListener( new ActionListener()
               @Override
               public void actionPerformed(ActionEvent e)
                    JPanelWithBackground currentObject = mainGame.getFacingObject();
                    if( currentObject instanceof EdibleItem )
                         //EdibleItem apple = ( EdibleItem )currentObject;
          controlPanel.add( eatButton );
          JButton attackButton = new JButton( "ATTACK" );
          attackButton.setFocusable( false );
          attackButton.addActionListener( new ActionListener()
               @Override
               public void actionPerformed(ActionEvent e)
                    System.out.println( "Remove" );
                    mainFrame.getContentPane().remove( mainEntrance );
                    mainEntrance.setBounds( 0,0,0,0);
//                    mainFrame.add( forest );
                    mainFrame.validate();
                    mainFrame.repaint();
          controlPanel.add( attackButton );
          mainFrame.setVisible( true );
          mainFrame.requestFocusInWindow();
}I know that my code is a mess, because it is connected with many classes and the quality of the format is not very good. But I will refactor it later when I solved the problem.
The problem is I have a JPanel with a character and an apple in it. I could not use any other layout, I have to use absolute layout, because I the user can control the character but arrow keys. And the character moves in pixels.
Here what I wanted to do.
final Room mainEntrance = new Room( "at the main entrance of the deep forest" );
          mainEntrance.setBackground( Color.white );
          mainEntrance.setLayout( null );
          mainEntrance.setExit( Direction.UP, null );Room extends JPanel, I wanted to delete this panel when I clicked this button
          JButton attackButton = new JButton( "ATTACK" );
          attackButton.setFocusable( false );
          attackButton.addActionListener( new ActionListener()
               @Override
               public void actionPerformed(ActionEvent e)
                    System.out.println( "Remove" );
                    mainFrame.getContentPane().remove( mainEntrance );
                    mainEntrance.setBounds( 0,0,0,0);
//                    mainFrame.add( forest );
                    mainFrame.validate();
                    mainFrame.repaint();
          controlPanel.add( attackButton );Like I said before, I tried validate, repaint and setBounds to all 0s. Nothing happened with the Room class. How do I delete that Room.
Thank you so much.