Thread: JScrollPane (/Scrollbar) not working on my grid

I have the following code:

import java.awt.*;
import javax.swing.*;
 
/**@name DApplet version 0.9 
 * @made by Vinvar la Lece
 */
public class TestForum extends JFrame {
	TestForum() {
		this.setSize(1024, 768);
		this.setTitle("DApplet");
		this.setBackground(Color.LIGHT_GRAY);
		this.getContentPane().add(new DApplet(true), BorderLayout.CENTER);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
	}
 
	public static void main(String[] args) { 
		new DKApplic().setVisible(true);
	}
 
	private static final long serialVersionUID = 1;
 
	/*
	 * Private class called in TestForum()
	 */
	private class DApplet extends JApplet {
		boolean isDeelVanApplicatie;
 
		JScrollPane mainScrollFrame;
 
		public DApplet() {
			this(false);
		}
 
		DApplet(boolean app) {
			this.isDeelVanApplicatie = app;
			if (app) {
				this.init();
			}
		}
 
		public void init() {
			this.setLayout(new BorderLayout());
 
			// Creating and adding playfield
			DPlayfield playfield = new DPlayfield();
			// The playfield can be larger then the screen.
			// Therefore, we need to add a  scrollable layer beneath the playfield on which we add the playfield
			mainScrollFrame = new JScrollPane(playfield);
			// Make sure that you can scroll within the playfield
			playfield.setViewport(mainScrollFrame.getViewport());
			// Add the scrollpane
			this.add(mainScrollFrame, BorderLayout.CENTER);
 
 
			// Extra's to be deleted when it works
			mainScrollFrame.setHorizontalScrollBarPolicy(mainScrollFrame.HORIZONTAL_SCROLLBAR_ALWAYS);
		}
 
 
		private static final long serialVersionUID = 1L;
	}
 
	/*
	 * Private class called in DApplet() -> init()
	 */	
	private class DPlayfield extends JComponent {
		JViewport viewport;
 
		int boxSize = 50, numberOfRows = 20, numberOfColumns = 10;
		int width = numberOfRows * boxSize - boxSize;
		int height = numberOfColumns * boxSize - boxSize;
 
		public DPlayfield() {
			JLabel label = new JLabel();
			label.setText("Welkom. Nog meer tekst om alles op te vullen en scrollpane te testen. Is dit genoeg?");
 
			this.add(label);
		}
 
		public void setViewport(JViewport vp) {
			this.viewport = vp;		
		}
 
		@Override
		public void paintComponent(Graphics g) {
			super.paintComponent(g);
			update(g);
		}
 
		public void update(Graphics g) {
			drawGrid(g);
		}
 
		private void drawGrid(Graphics g) {
			g.setColor(Color.BLACK);
			for (int i = 0; i < numberOfRows; i++) {
				g.drawLine(i * boxSize, 0, i * boxSize, height);
			}
			for (int i = 0; i < numberOfColumns; i++) {
				g.drawLine(0, i * boxSize, width, i * boxSize);
			}
		}
 
		private static final long serialVersionUID = 1L;
	}
}

I simplified the code so it is just my problem with the grid.

I want that scrollbars appear if the screensize is smaller then the grid. Unfortunally, I can't get it working (and I was working on it this whole weekend). Is there anybody who has an idea?

I am sorry. Did not know that the forums where releated. I tried to delete the other thread. But I couldn't delete it (or this one). Feel free to delete one of them.

Nonetheless, do you know the answer to my question?

I'm having... more or less the same problem- MchessBox is a fairly simple class that extends JComponent. It's larger than the screen, so I tried to put it inside a JScrollPane to give it scroll bars... which just doesn't seem to work at all- there's no scroll bars anywhere on the screen, it's just behaving as if I added the MchessBox directly instead of putting it inside the JScrollPane. I can't seem to get the scroll bars to show at all, here.

        private MchessBox box;
	private JScrollPane scroll;
 
	/**
	 * Default constructor that sets up an instance of the game.
	 */
	public MchessFrame(){
 
		super("Mechachess");
		Container window = getContentPane();
		setLayout(new BorderLayout());
		box = new MchessBox("files/maps/test1.txt"); //constructs the MchessBox, which is larger than 500x500
		scroll = new JScrollPane(box);
                window.setPreferredSize(new Dimension(500, 500));
		window.add(scroll,BorderLayout.CENTER);
        }

Am I doing something wrong with, like, sizes or something? Or is it a more particular problem with the way I'm setting up the JScrollPane?