Increment an object name within a loop

Question

I am using a for loop to create a grid of 60 JButtons. What I want to do is have the name of the actionListener increment each time the loops runs:

for (int y = 0; y < game.getHeight(); y++) {
        for (int x = 0; x < game.getWidth(); x++) {
            JButton square = new JButton();
            square.setFont(new Font("Verdana", Font.PLAIN, 20));
            ActionListener bh = new button_handler();
            square.addActionListener(bh);
            grid.add(square);
        }

So I would like the name to increment (bh_1, bh_2, bh_3, etc).

Thanks!

I get the question, and this can probably be done with reflection, but why would you want to change the name of the ActionListener variable here? That "name" is just a local reference and won't survive the scope of the loop iteration anyways, unless there's missing code here. — Ben Zotto
– Ben Zotto, Commented Jan 25, 2011 at 15:43
I don't think he wants to save the "name", since he's not setting the name at all. I think it's more that he wants references to the variables for later. — Erick Robertson
– Erick Robertson, Commented Jan 25, 2011 at 15:51

jjnguy · Accepted Answer · 2011-01-25 15:46:00Z

3

If your goal is to be able to keep track of the ActionListeners by name after creation, then you will want to use an array to do this. (If this is not why you want to name them differently, then I will need some more info.)

Assume you have an ActionListener[60] called actionListeners and a counter called buttonCount.

JButton square = new JButton();
square.setFont(new Font("Verdana", Font.PLAIN, 20));
ActionListener bh = new button_handler();
actionListeners[buttonCount++] = bh; // store the handler in an array for later
square.addActionListener(bh);
grid.add(square);

Now you will be able to access the ActionListeners from the array.

answered Jan 25, 2011 at 15:46

jjnguy

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Comments

Cuga · Accepted Answer · 2011-01-25 15:47:18Z

0

I'd recommend using a list:

LinkedList<ActionListener> actionListeners = new LinkedList<ActionListener>();

for (int y = 0; y < game.getHeight(); y++) {
    for (int x = 0; x < game.getWidth(); x++) {
        JButton square = new JButton();
        square.setFont(new Font("Verdana", Font.PLAIN, 20));
        ActionListener bh = new button_handler();

        // can access this action listener via actionListeners.get(indexNumber).
        actionListeners.add(bh);

        square.addActionListener(bh);
        grid.add(square);
    }

answered Jan 25, 2011 at 15:47

Cuga

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Comments

Erick Robertson · Accepted Answer · 2011-01-25 15:49:53Z

Store them in a two-dimensional array.

You could store these in any array, but I think storing them in a two-dimensional array makes sense since you have a grid of buttons and a grid of handlers. I also think it's a good idea to keep the reference to the buttons and the handlers. This will allow you to tweak the buttons as well as the button handlers at any later time.

Here is an example of how to do this:

JButton[][] squares = new JButton[game.getWidth()][game.getHeight()];
ActionListener[][] bhs = new ActionListener[game.getWidth()][game.getHeight()];
for (int y = 0; y < game.getHeight(); y++) {
  for (int x = 0; x > game.getWidth(); x++) {
    squares[x][y] = new JButton();
    squares[x][y].setFont(new Font("Verdana", Font.PLAIN, 20));
    ActionListener bhs[x][y] = new button_handler();
    squares[x][y].addActionListener(bhs[x][y]);
    grid.add(squares[x][y]);

  }
}

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