How to Efficiently Get the X and Y Indexes of a Button in a Java GridLayout?

How to Easily Get X and Y Indexes of a Button in a GridLayout

When working with a GridLayout in Java, you may encounter the need to determine the x and y indexes of a specific button within the grid. The conventional method involves a nested loop iterating through a bidimensional array of buttons to find the one you're looking for.

<br>  @Override<br>  public void actionPerformed(ActionEvent ae) {</p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">JButton bx = (JButton) ae.getSource();
for (int i = 0; i < 5; i++)
  for (int j = 0; j < 5; j++)
    if (b[i][j] == bx)
    {
      bx.setBackground(Color.RED);
    }

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}

This approach can be tedious and error-prone. Fortunately, there's a more efficient way to retrieve the button's coordinates.

Introducing the GridButtonPanel Class

The following Java code showcases a simplified solution:

<br>import java.awt.EventQueue;<br>import java.awt.GridLayout;<br>import java.awt.event.ActionEvent;<br>import java.awt.event.ActionListener;<br>import java.util.ArrayList;<br>import java.util.List;<br>import javax.swing.JButton;<br>import javax.swing.JFrame;<br>import javax.swing.JPanel;</p><p>/**</p>

• @see http://stackoverflow.com/questions/7702697
  */

public class GridButtonPanel {

private static final int N = 5;
private final List<JButton> list = new ArrayList<JButton>();

private JButton getGridButton(int r, int c) {
    int index = r * N + c;
    return list.get(index);
}

private JButton createGridButton(final int row, final int col) {
    final JButton b = new JButton("r" + row + ",c" + col);
    b.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            JButton gb = GridButtonPanel.this.getGridButton(row, col);
            System.out.println("r" + row + ",c" + col
                + " " + (b == gb)
                + " " + (b.equals(gb)));
        }
    });
    return b;
}

private JPanel createGridPanel() {
    JPanel p = new JPanel(new GridLayout(N, N));
    for (int i = 0; i < N * N; i++) {
        int row = i / N;
        int col = i % N;
        JButton gb = createGridButton(row, col);
        list.add(gb);
        p.add(gb);
    }
    return p;
}

private void display() {
    JFrame f = new JFrame("GridButton");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.add(createGridPanel());
    f.pack();
    f.setLocationRelativeTo(null);
    f.setVisible(true);
}

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {

        @Override
        public void run() {
            new GridButtonPanel().display();
        }
    });
}

}

In this code:

1. getGridButton() Method:

Using this method, you can retrieve a button from the grid based on its x and y coordinates. To determine the index in the list, it multiplies the number of rows (N) by the specified row (r) and adds the specified column (c).

2. Action Listener:

When a button is clicked, the action listener is triggered and invokes the getGridButton() method to retrieve the clicked button. It then compares the reference of the clicked button (b) to the retrieved button (gb) to ensure they both represent the same button.

3. display() Method:

This method creates the graphical user interface (GUI) and displays it.

When you run this program, the GUI displays a grid with buttons containing their x and y coordinates. Upon clicking any button, the console prints its coordinates and confirms the button's identity.

For Example:

If you click the button labeled "r2,c3", the console output will be:

r2,c3 true true

This demonstrates that the retrieved button (gb) is identical to the clicked button (b), indicating a successful operation.

Using this approach, you can avoid the complex nested looping process and efficiently access the x and y indexes of buttons in a GridLayout.

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