Making a JPanel manually resizable

Question

I have a JFrame with BorderLayout as the layout manager.

In the south border, I have a JPanel, I want this JPanel

Answer 1

I think you meant to say JPanel. You can add a custom mouseListener and handle mouse clicks, drags and mouse releases and then resize the panel programmaticaly.

This will demonstrate this. Note that the jframe does NOT resize automatically with the JPanel. To make the effect more visible i painted the panel red and added a beveled border :

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.BevelBorder;

@SuppressWarnings("serial")
public class ResizablePanel extends JPanel {

    private boolean drag = false;
    private Point dragLocation  = new Point();

    public  ResizablePanel() {
        setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
        setPreferredSize(new Dimension(500, 500));
        final JFrame f = new JFrame("Test");
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                drag = true;
                dragLocation = e.getPoint();
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                drag = false;
            }
        });
        addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                if (drag) {
                    if (dragLocation.getX()> getWidth()-10 && dragLocation.getY()>getHeight()-10) {
                        System.err.println("in");
                        setSize((int)(getWidth()+(e.getPoint().getX()-dragLocation.getX())),
                                (int)(getHeight()+(e.getPoint().getY()-dragLocation.getY())));
                        dragLocation = e.getPoint();
                    }
                }
            }
        });
        f.getContentPane().setLayout(new BorderLayout());
        f.getContentPane().add(this,BorderLayout.CENTER);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
    }

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

    public void paintComponent(Graphics g) {
        g.setColor(Color.red);
        g.fillRect(0, 0, getWidth(), getHeight());
    }

}