ActionListener of JComboBox and initialize JPanel

Question

I want to write program in which you can chance scene ( JPanel ) thanks to JComboBox . I used ActionListener , but it doesn't work.

At the beginning of constructor I defined panel as final, but it didn't help.

scene.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        String choice = String.valueOf(scene.getSelectedItem());
        if(choice=="Sceneria"||choice=="Scene"){
            slider.setEnabled(false);
            panel = new JPanel();// problem here
        }
    }
});

Error

The final local variable panel cannot be assigned, since it is defined in an enclosing type

Answer 1

I suggest you to make panel an attribute of your class. Then call panel such as YourClass.this.panel .

public class YourClass {

    private JPanel panel;

    public YourClass() {

        // ...

        scene.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String choice = String.valueOf(scene.getSelectedItem());
                if(choice.equals("Sceneria") || choice.equals("Scene")) {
                    slider.setEnabled(false);
                    YourClass.this.panel = new JPanel();
                    YourClass.this.panel.revalidate();
                    YourClass.this.panel.repaint();
                }
            }
        });
    }
}