JavaFX event handler for array

Question

All this rectangles are added in grid and I want after click each of them to change the color to white, but program throwing and exception.

Can i do this with this way or I need to get the position of rectangle a make on his place a new one ?

Rectangle[] rec = new Rectangle[22 * 12];
    for( int i = 0; i < 22 * 12; i++){
        rec[i] = new Rectangle(32, 32);
        rec[i].setStroke(Color.BLACK);
        rec[i].setFill( Color.valueOf("#202020") );
        rec[i].setStrokeWidth(1);
        rec[i].setOnMouseClicked(e -> {
            Rectangle r = new Rectangle(32, 32, Color.WHITE);
            rec[i].setFill( Color.WHITE); // exception at this line -> i must be final or ...
        });

}

That's a compile error, not an exception.

James_D
– James_D

2016-01-04 18:46:07 +00:00
Commented Jan 4, 2016 at 18:46 — James_D
– James_D, Commented Jan 4, 2016 at 18:46

James_D · Accepted Answer · 2016-01-04 18:47:56Z

1

As your compile error says, you can't access non-final variables in a lambda expression. You can get around this by putting your rectangle in a different (effectively-final) variable:

Rectangle[] rec = new Rectangle[22 * 12];
    for( int i = 0; i < 22 * 12; i++){
        Rectangle r = new Rectangle(32, 32);
        r.setStroke(Color.BLACK);
        r.setFill( Color.valueOf("#202020") );
        r.setStrokeWidth(1);
        r.setOnMouseClicked(e -> {
            r.setFill( Color.WHITE); 
        });

        rec[i] = r ;
    }

}

answered Jan 4, 2016 at 18:47

James_D

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