Question

I have this code that loads 5 images and puts them into the frame using FlowLayout:

public class Main
{
    private static final int verticalGap=50;
    private static final int horizontalGap=30;
    private static final int width= 800;
    private static final int height= 800;
    public static void main(String[] args)
    {
        FlowLayout layout=new FlowLayout(FlowLayout.LEADING,horizontalGap,verticalGap);
        JButton button= new JButton("Discard");
        ImagePanel[] panels= new ImagePanel[5];
        Deck deck= new Deck();
        JFrame frame= new JFrame("Poker");
        frame.setSize(width, height);
        frame.setLayout(layout);
        frame.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
        deck.mix();
        for(int i=0; i<5; i++)
        {
            panels[i]= new ImagePanel();
            panels[i].setImage(deck.getCard(i));
            frame.getContentPane().add(panels[i]);
        }
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

The code loads 5 cards and spot them correctly.
But the problem is that now I want to place a button to the frame.This button should be placed approximately in the center of the screen, but if I add it to the pane, the button is placed near the other panels, using the horizontal gap that the flow layout has set.
How do I place it in an absolute position without altering the position of the panels (so I want 5 panels to be added using flow layout, and one button to be added in an absolute position).

Answer 1

You can’t mix absolute-layout with a LayoutManager.

In this case:

1. I would wrap the 5 cards in a separate JPanel (using your FlowLayout).
2. I would put that panel in the content pane.
3. and use another JPanel for the button which I would add to the SOUTH of the content pane (by default the content pane uses BorderLayout). In this panel, I would simply use a FlowLayout with the alignement set to CENTER.
4. Move your GUI init code to the EDT by using SwingUtilities.invokeLater (always run GUI things on the EDT!)

Here is the code corresponding to that solution (but I could not test it because I don’t have your other classes).

import java.awt.BorderLayout;
import java.awt.ComponentOrientation;
import java.awt.FlowLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Main {
    private static final int verticalGap = 50;
    private static final int horizontalGap = 30;
    private static final int width = 800;
    private static final int height = 800;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new Main().initUI();
            }
        });
    }

    private void initUI() {
        FlowLayout layout = new FlowLayout(FlowLayout.LEADING, horizontalGap, verticalGap);
        JButton button = new JButton("Discard");
        ImagePanel[] panels = new ImagePanel[5];
        Deck deck = new Deck();
        JFrame frame = new JFrame("Poker");
        frame.setSize(width, height);
        frame.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
        deck.mix();
        JPanel deckPanel = new JPanel(layout);
        for (int i = 0; i < 5; i++) {
            panels[i] = new ImagePanel();
            panels[i].setImage(deck.getCard(i));
            deckPanel.add(panels[i]);
        }
        frame.getContentPane().add(deckPanel);
        JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
        buttonPanel.add(button);
        frame.getContentPane().add(buttonPanel, BorderLayout.SOUTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();// Sets the frame size to its preferred size.
        // You can also call setSize() instead
        frame.setVisible(true);
    }
}