Thread: Drawing on a swing frame

Hello everyone!


I've recently tried to get swing frames working but the obstacle now is that I want to be able to move a rectangle on the screen.

My first step was creating a rectangle which got drawn at the start on mouse x and y position:

import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.*; 
import java.awt.MouseInfo;
 
public class MainWindowtestagain {
 
 
    public static void main(String[] args){
 
 
 
                SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
 
 
 
        }
                    private static void createAndShowGUI(){
              System.out.println("Created GUI on EDT? "+
               SwingUtilities.isEventDispatchThread());
               JFrame f = new JFrame("Swing Paint Demo");
              f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
              f.add(new MyPanel());
              f.pack();
              f.setVisible(true);
                }
}
 
 
class MyPanel extends JPanel {
 
    public MyPanel() {
        setBorder(BorderFactory.createLineBorder(Color.blue));
    }
 
    public Dimension getPreferredSize() {
        return new Dimension(640,480);
    }
 
 
    ////
 
 
    ////
 
 
 
 
 
    public void paintComponent(Graphics g) {
        super.paintComponent(g);    
        int rectx=77;
        int recty=66;
 
        // Draw Text
      //g.drawString("("+xpos+","+ypos+")",xpos,ypos);
 
            PointerInfo a = MouseInfo.getPointerInfo();
Point b = a.getLocation();
int x = (int) b.getX();
int y = (int) b.getY();
        g.setColor(Color.black);
        g.drawString("This is my custom Panel!",10,20);
        g.setColor(Color.red);
        //g.drawRect(x/*x1*/, y/*y1*/, 32/*x2*/, 32 /*x2*/);
        g.drawLine(x, y-32, x+32, y-32);
        g.drawLine(x, y, x, y-32);
        g.drawLine(x+32, y, x+32, y-32);
        g.drawLine(x, y, x+32, y);
 
        g.setColor(Color.cyan);
        g.drawLine(140, 90, 86, 349);
        g.drawString(x+"  "+y,32,16);
 
 
    }
 
    }
    }

but then I wanted it to happen every step so I tried to create a loop:

import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
 
import java.awt.*; 
import java.awt.MouseInfo;
 
public class MainWindowtestagain {
 
 
    public static void main(String[] args){
 
 
 
                SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
 
 
 
        }
                    private static void createAndShowGUI(){
              System.out.println("Created GUI on EDT? "+
               SwingUtilities.isEventDispatchThread());
               JFrame f = new JFrame("Swing Paint Demo");
              f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
              f.add(new MyPanel());
              f.pack();
              f.setVisible(true);
                }
}
 
 
class MyPanel extends JPanel {
 
    public MyPanel() {
        setBorder(BorderFactory.createLineBorder(Color.blue));
    }
 
    public Dimension getPreferredSize() {
        return new Dimension(640,480);
    }
 
 
    ////
 
 
    ////
 
 
 
 
 
    public void paintComponent(Graphics g) {
        super.paintComponent(g);    
        int rectx=77;
        int recty=66;
 
        // Draw Text
      //g.drawString("("+xpos+","+ypos+")",xpos,ypos);
        int ii = 0;
        while (ii < 234823)
        {
            PointerInfo a = MouseInfo.getPointerInfo();
Point b = a.getLocation();
int x = (int) b.getX();
int y = (int) b.getY();
        g.setColor(Color.black);
        g.drawString("This is my custom Panel!",10,20);
        g.setColor(Color.red);
        //g.drawRect(x/*x1*/, y/*y1*/, 32/*x2*/, 32 /*x2*/);
        g.drawLine(x, y-32, x+32, y-32);
        g.drawLine(x, y, x, y-32);
        g.drawLine(x+32, y, x+32, y-32);
        g.drawLine(x, y, x+32, y);
 
        g.setColor(Color.cyan);
        g.drawLine(140, 90, 86, 349);
        g.drawString(x+"  "+y,32,16);
 
        ii+=1;
 
        }
    }
 
    }

but the program refused to show the images until i closed it, must be some sort of lag.

What should I do?