JPanel.addComponentListener does not work when the listener is a class variable
- by Coder
I have a public class which has the following method and instance variable:
public void setImagePanel(JPanel value) {
imagePanel = value;
if (imagePanel != null) {
//method 1 : works
imagePanel.addComponentListener(new ComponentAdapter() {
public void componentResized(ComponentEvent evt) {
System.out.println("Here 1");
}
});
//method 2 : does not work
panelResizeListener = new ResizeListener();
imagePanel.addComponentListener(panelResizeListener);
//method 3 : works
//ResizeListener listener = new ResizeListener();
//imagePanel.addComponentListener(listener);
//method 4 : works
//imagePanel.addComponentListener(new ResizeListener());
//method 5 : does not work -- THIS IS THE DESIRED CODE I WANT TO USE
imagePanel.addComponentListener(panelResizeListener);
}
}
public class ResizeListener extends ComponentAdapter {
@Override
public void componentResized(ComponentEvent evt) {
System.out.println("RESIZE 3");
}
}
private ResizeListener panelResizeListener = new ResizeListener();
Each of the methods above correspond the to code immediately below until the next //method comment. What i don't understand is why i can't use the class instance variable and add that to the JPanel as a component listener.
What happens in the cases above where i say that the method does not work is that i don't get the "RESIZE 3" log messages. In all cases where i list that it works, then i get the "RESIZE 3" messages.
The outer class is public with no other modification except that it implements an interface that i created (which has no methods or variables in common with the methods and variables listed above).
If anyone can help me i would greatly appreciate it. This problem makes no sense to me, the code should be identical.
