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Debug: Accessing function variables from inner classes not possible [message #252212]

Tue, 25 March 2008 15:39

Eclipse User

Originally posted by: higherfalling.googlemail.com

Hello,

is it possible to access / inspect member variables of a function in an
anonymous inner class like below in following code example? When i put a
breakpoint to the actionPerformed method i cannot access the variables
from the constructor. Is this a bug or some configuration work?

Thanks for your advice

Frank

public class SwingTest {

SwingTest(){
JFrame frame = new JFrame("HelloWorldSwing");
final JLabel label = new JLabel("Some text");
JButton button = new JButton("Click");
final JTextField textField = new JTextField();
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
label.setText("You entered: "+ textField.getText());

}
});
frame.getContentPane().setLayout( new GridLayout());
frame.getContentPane().add(textField);
frame.getContentPane().add(button);
frame.getContentPane().add(label);
frame.pack();
frame.setVisible(true);
}

public static void main(String[] args) {
SwingTest swingTest = new SwingTest();
}
}

Re: Debug: Accessing function variables from inner classes not possible [message #252216 is a reply to message #252212]

Tue, 25 March 2008 15:41

Eclipse User

Originally posted by: higherfalling.googlemail.com

I forgot: I use eclipse 3.3.2

Re: Debug: Accessing function variables from inner classes not possible [message #252260 is a reply to message #252212]

Wed, 26 March 2008 09:32

Eclipse User

Originally posted by: eclipse-news.rizzoweb.com

Frank wrote:
> Hello,
>
> is it possible to access / inspect member variables of a function in an
> anonymous inner class like below in following code example? When i put a
> breakpoint to the actionPerformed method i cannot access the variables
> from the constructor. Is this a bug or some configuration work?

This can't work the way you want. The problem is that the c'tor
variables are out of scope at the time when actionPerformed() is called
(it is called by the Swing event thread in response to an event on the
JButton). In order to make them in scope in actionPerformed() you'd have
to refer to them in that method (which will only work for the ones that
are declared final, by the way).

Hope this helps,
Eric

> public class SwingTest {
>
> SwingTest(){
> JFrame frame = new JFrame("HelloWorldSwing");
> final JLabel label = new JLabel("Some text");
> JButton button = new JButton("Click");
> final JTextField textField = new JTextField();
> button.addActionListener(new ActionListener(){
> public void actionPerformed(ActionEvent e) {
> label.setText("You entered: "+
> textField.getText()); }
> }); frame.getContentPane().setLayout( new GridLayout());
> frame.getContentPane().add(textField);
> frame.getContentPane().add(button);
> frame.getContentPane().add(label);
> frame.pack();
> frame.setVisible(true);
> }
> public static void main(String[] args) {
> SwingTest swingTest = new SwingTest();
> }
> }
>
>

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