Making JPanel Highlighted when clicked

Question

So I have a couple Jpanels in my frame, and the idea is that, when one of the panels is selected, it will be highlighted. This is just the first step, because in the end, I want to be able to have buttons that act on the panels, but only the one that is highlighted.

I'm thinking that I want some kind of mouselistener on the panels, but I'm not sure how to implement this to get the results I want.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.Border;

public class CustomComponent {
    Border emptyBorder  = BorderFactory.createEmptyBorder(1,1,1,1);
    Border selectBorder = BorderFactory.createLineBorder(Color.blue);
    JPanel[] panels;

    private JPanel getContent() {
        JLabel label = new JLabel();
        label.setText("fffffffff");
        label.setBounds(5, 5, 25, 25);

        JLabel label2 = new JLabel();
        label2.setText("HHHHHHHHHH");
        label2.setBounds(25, 25, 25, 25);

        JLabel label3 = new JLabel();
        label3.setText("YYYYYYYY");
        label3.setBounds(50, 50, 25, 25);

        JPanel mainPanel = new JPanel();
        mainPanel.setSize(new Dimension(300,300));
        JPanel panel1 = new JPanel();
        panel1.add(label);
        JPanel panel2 = new JPanel();
        panel2.add(label2);
        JPanel panel3 = new JPanel();
        panel3.add(label3);

        panel1.setBackground(Color.WHITE);
        panel2.setBackground(Color.MAGENTA);
        panel3.setBackground(Color.orange);

        panel1.setBorder(emptyBorder);
        panel2.setBorder(emptyBorder);
        panel3.setBorder(emptyBorder);

        panels = new JPanel[] { panel1, panel2, panel3 };

        mainPanel.add(panel1);
        mainPanel.add(panel2);
        mainPanel.add(panel3);
        return mainPanel;
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new CustomComponent().getContent());
        frame.pack();
        frame.setVisible(true);
    }
}

Answer 1

Here is a sample code to show how to implement highlighting when mouse is over one of the JPanel. If you would want to highlight on click rather than on hover then implement the mousePressed and mouseReleased methods instead of mouseEntered and mouseExited

import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

public class MouseHoverDemo
{
    public static void main(String[] args)
    {
        new MouseHoverDemo();
    }

    MouseHoverDemo()
    {
        JFrame jFrame = new JFrame("Mouse Hover Demo");
        jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        jFrame.setLayout(new GridLayout(5,5));
        for(int i=0;i<25;i++) jFrame.add(new CustomPanel());
        jFrame.pack();
        jFrame.setLocationRelativeTo(null);
        jFrame.setVisible(true);
    }

    class CustomPanel extends JPanel implements MouseListener
    {
        Border blackBorder = BorderFactory.createLineBorder(Color.BLACK);
        Border redBorder = BorderFactory.createLineBorder(Color.RED,5);
        CustomPanel()
        {
            addMouseListener(this);
            setBorder(blackBorder);
            setFocusable(true);
        }

        @Override
        public Dimension getPreferredSize()
        {
            return new Dimension(50, 50);
        }

        @Override public void mouseClicked(MouseEvent e){}
        @Override public void mousePressed(MouseEvent e){}
        @Override public void mouseReleased(MouseEvent e){}

        @Override
        public void mouseEntered(MouseEvent e)
        {
            setBorder(redBorder);
        }

        @Override
        public void mouseExited(MouseEvent e)
        {
            setBorder(blackBorder);
        }
    }
}

---

UPDATE

For your newly required functionality change the code of customPanel to this

class CustomPanel extends JPanel implements MouseListener
    {
        boolean isHighlighted;
        Border blackBorder = BorderFactory.createLineBorder(Color.BLACK);
        Border redBorder = BorderFactory.createLineBorder(Color.RED,5);
        CustomPanel()
        {
            addMouseListener(this);
            setBorder(blackBorder);
            setFocusable(true);
        }

        @Override
        public Dimension getPreferredSize()
        {
            return new Dimension(200, 100);
        }

        @Override public void mouseClicked(MouseEvent e)
        {
            if(isHighlighted) setBorder(blackBorder);
            else setBorder(redBorder);
            isHighlighted=!isHighlighted;
        }

        @Override public void mousePressed(MouseEvent e){}
        @Override public void mouseReleased(MouseEvent e){}
        @Override public void mouseEntered(MouseEvent e){}
        @Override public void mouseExited(MouseEvent e){}
    }