Class extending JLabel doesn't follow the layout of the container

Question

I'm trying to create a Sudoku app in Eclipse using WindowBuilder. I decided to use JLabels as cells. I have a class Cell that extends JLabel and adds 3 fields - value, x and y. The Cells are places in 9 JPanels with GridLayout.

The problem is that when I add Cells into the JPanels, they look like they are stacked on top of each other, as if the GridLayout is not working. When I do the same with JLabels instead, they look fine.

With Cells:

With JLabels:

This is the Cell class:

import javax.swing.JLabel;

public class Cell extends JLabel {


private static final long serialVersionUID = 1L;
private int value;
private int x;
private int y;

public Cell(int value, int x, int y) {
    super(Integer.toString(value));
    this.value = value;
    this.x = x;
    this.y = y;
}

public Cell(int value) {
    this.value = value;
}

public int getValue() {
    return value;
}

public void setValue(int value) {
    this.value = value;
}

public int getX() {
    return x;
}

public void setX(int x) {
    this.x = x;
}

public int getY() {
    return y;
}

public void setY(int y) {
    this.y = y;
}

}

Below is the MainFrame class. I'm changing two lines in the initialize() method. It works fine with

JLabel cell = new JLabel(Integer.toString(j));

but not with

JLabel cell = new Cell(j, j, i);

The full MainFrame class:

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
import javax.swing.border.LineBorder;


public class MainFrame {

private JFrame frame;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                MainFrame window = new MainFrame();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public MainFrame() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    frame.setResizable(false);
    frame.setBounds(100, 100, 458, 532);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(new GridLayout(1, 0, 0, 0));

    JPanel mainPanel = new JPanel();
    mainPanel.setForeground(Color.WHITE);
    mainPanel.setBorder(new LineBorder(new Color(0, 0, 0), 2));
    mainPanel.setBounds(10, 61, 422, 422);
    frame.getContentPane().add(mainPanel);
    mainPanel.setLayout(new GridLayout(3, 0, 0, 0));

    JPanel[] bigSquares = new JPanel[9];

    for (int i=0; i < 9; i++) {

        bigSquares[i] = new JPanel();
        mainPanel.add(bigSquares[i]);
        bigSquares[i].setBorder(new LineBorder(new Color(0, 0, 0), 2));
        bigSquares[i].setLayout(new GridLayout(3, 0, 0, 0));


        for (int j=0; j < 9; j++) {

            JLabel cell = new Cell(j, j, i);
            //JLabel cell = new JLabel();

            cell.setBorder(new LineBorder(new Color(0, 0, 0), 1));
            cell.setVerticalAlignment(SwingConstants.CENTER);
            cell.setHorizontalAlignment(SwingConstants.CENTER);
            cell.setFont(new Font("Tahoma", Font.PLAIN, 14));

            bigSquares[i].add(cell);
        }
    }


}
}

Answer 1

The problem is that JLabel already has getX() and getY() methods (actually, the methods are from JComponent. See the JavaDoc for getX().

The orignal methods

Returns the current x/y coordinate of the component's origin

By overwriting getX and getY you are actually defining components coordinates relative to it's parent container.

---

One solution would be to rename your methods to getCellX, getCellY.

Another solution would be to work with a separate class Cell that has a value, coordinates x, y and a JLabel for displaying the value.