Use non-local variables in actionlistener
I want to use a variable in an action. this is my code:
public class Face {
public Face(){
Btn1 = new JToggleButton();
Btn2 = new JToggleButton();
Btn3 = new JToggleButton();
Btn4 = new JToggleButton();
Btn5 = new JToggleButton();
Btn6 = new JToggleButton();
}
public Start6(){
JToggleButton[] Btn = new javax.swing.JToggleButton[5]; // An array for saving address of all buttons
Btn[0] = Btn1 ;
Btn[1] = Btn2 ;
Btn[2] = Btn3 ;
Btn[3] = Btn4 ;
Btn[4] = Btn5 ;
Btn[5] = Btn6 ;
for (int i = 0 ; i < 36 ; i++) {
Btn[i].addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
Btn[i].setSize(150, 150);
ImageIcon BtnImage = new ImageIcon(getClass().getResource("/GameImages/" + /* a picture name*/ + ".jpg" ));
Image img = BtnImage.getImage();
Btn[i].setIcon( new ImageIcon(img.getScaledInstance(225,160 ,Image.SCALE_FAST)));
X6P.add(Btn[i]);
}
});
}
}
public javax.swing.JToggleButton Btn1;
public javax.swing.JToggleButton Btn2;
public javax.swing.JToggleButton Btn3;
public javax.swing.JToggleButton Btn4;
public javax.swing.JToggleButton Btn5;
}
when i want to use from Btn array in Btn array action manifest (same arrays) i get this error:
local variables referenced by the inner class must be final or effectively final I want the icon to be displayed when the button is clicked ...
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The error means what it says: your array variable is Btn
not final
, so it cannot be accessed to the inner class. Crafting final
fixes the problem:
final JToggleButton[] Btn = new ...
Another solution would be to move the array to a class:
public javax.swing.JToggleButton Btn1;
public javax.swing.JToggleButton Btn2;
public javax.swing.JToggleButton Btn3;
public javax.swing.JToggleButton Btn4;
public javax.swing.JToggleButton Btn5;
private javax.swing.JToggleButton[] Btn = new javax.swing.JToggleButton[] {
Btn1, Btn2, Btn3, Btn4, Btn5
};
It will do the same and make your code shorter.
I want the icon to be displayed when the button is clicked
You don't need to use an array at all: instead of a link Btn[i]
, a link e.getSource()
. It's set to the button the button was clicked on - all you have to do is throw it:
javax.swing.JToggleButton sender = (javax.swing.JToggleButton)e.getSource();
Create one action listener outside the loop and set it on all of your buttons. This would eliminate the array entirely:
// The same listener instance can handle all buttons
ActionListener actListener = new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
javax.swing.JToggleButton senderButton = (javax.swing.JToggleButton)e.getSource();
... // Do anything you want with senderButton here
}
};
// Add the same listener to all buttons
for (int i = 0 ; i < 36 ; i++) {
Btn[i].addActionListener(actListener);
}
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