Trying to change a JPanel's backcolor...

I'm using Eclipse.

Code:

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import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.border.BevelBorder;


public class mainForm extends JFrame {

        private JPanel contentPane;

        /**
        * Launch the application.
        */
        public static void main(String[] args) {
                EventQueue.invokeLater(new Runnable() {
                        public void run() {
                                try {
                                        mainForm frame = new mainForm();
                                        frame.setVisible(true);
                                } catch (Exception e) {
                                        e.printStackTrace();
                                }
                        }
                });
        }

        /**
        * Create the frame.
        */
        public mainForm() {
                setTitle("Test");
                setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                setBounds(100, 100, 450, 300);
                contentPane = new JPanel();
                contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
                setContentPane(contentPane);
                contentPane.setLayout(null);
               
                JPanel panel = new JPanel();
                panel.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
                panel.addMouseListener(new MouseAdapter() {
                        @Override
                        public void mouseClicked(MouseEvent arg0) {
                                panel.setBackground(Color.black);
                       
                        }
                });
                panel.setBounds(112, 62, 91, 72);
                contentPane.add(panel);
        }
}

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On the line: "panel.setBackground(Color.black)", I'm getting the error: "Cannot refer to a non-final variable panel inside an inner class defined in a different method."

That error is correct: you cannot refer to a non-final local variable from within your anonymous MouseListener inner class. The reasons for this is due to the inner class making a local copy of the variable before using it, and if the variable is non-final then logic errors might occur. The simple solution: declare the panel JPanel variable final.

How do I get all panels on the contentPane?
Current code is something like this:

Code:

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for(int i=0;i<=contentPane.getComponentCount()-1;i++)
                {
                                        contentPane.getComponent(i).addMouseListener(ma);
                }

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How do I check the type of the Component? I only want the MouseListener to be added to JPanels.

Use instanceof to determine the type