Accessing locally defined JButtons in a GridLayout JPanel

Question

Lets say you have a GridLayout of JButtons in an NxN grid, in code such as this:

JPanel bPanel = new JPanel();
bPanel.setLayout(new GridLayout(N, N, 10, 10));
    for (int row = 0; row < N; row++)
    {
        for (int col = 0; col < N; col++)
        {
            JButton b = new JButton("(" + row + ", " + col + ")");
            b.addActionListener(new ActionListener()
            {
                public void actionPerformed(ActionEvent e)
                {

                }
            });
            bPanel.add(b);
        }
    }

How would one access each button individually in the grid to change the button's name through setText()? This needs to be done outside of actually pressing the button in question.

Because each button in instantiated locally as "b", a globally accessible name for each button is not possible at current. What could be done to access each button independently? Could an array like JButton[][] hold references to all the buttons? How can this be set up in the code above?

Any input is appreciated.

Thanks.

Probably duplicate of http://stackoverflow.com/questions/8394296/java-swing-gridlayout-accessing-specfic-coordinate — Ondrej Peterka, Apr 30 '12 at 13:43
See also this [Q&A](http://stackoverflow.com/q/7702697/230513). — trashgod, Apr 30 '12 at 15:23

score 7 · Accepted Answer · answered Apr 30 '12 at 14:21

7

you can,

1) putClientProperty

buttons[i][j].putClientProperty("column", i);
buttons[i][j].putClientProperty("row", j);
buttons[i][j].addActionListener(new MyActionListener());

and

public class MyActionListener implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent e) {
        JButton btn = (JButton) e.getSource();
        System.out.println("clicked column " + btn.getClientProperty("column")
                + ", row " + btn.getClientProperty("row"));
}

2) ActionCommand

answered Apr 30 '12 at 14:21

mKorbel

109,525
20
134
319

Oh, that is neat! All internal to putClientProperty. I might try this rather than an array of JButton references. Thanks! – Avertheus Apr 30 '12 at 14:38
You don't need an instance of MyActionListener for each button. One instance would work for all the buttons. Otherwise, an excellent answer. – Gilbert Le Blanc Apr 30 '12 at 14:53
Hm putClientProperty. I learn something new from you with every post! – Hovercraft Full Of Eels Oct 20 '12 at 19:55

score 3 · Answer 2 · answered Apr 30 '12 at 13:44

3

You can create an array (or list or something else) to store all the buttons. Or you can use public Component[] getComponents() method of the bPanel (Container).

answered Apr 30 '12 at 13:44

StanislavL

56,971
9
68
98

Accessing locally defined JButtons in a GridLayout JPanel

2 Answers2

Linked