Swing Graphics on JFrame

Using Java Graphics, I tried to draw a simple rectangle.

How Applet

it works well, but when I use it to display on JFrame

, the rectangle zooms in, but with some kind of unusual background

Here is the code:

package graphicsex;

import java.awt.Graphics;

public class Graphics2 extends javax.swing.JFrame {

    public static void main(String[] args) {
        Graphics2 inst = new Graphics2();
        inst.setVisible(true);
    }

    public Graphics2() {
        super();
        initGUI();
    }

    private void initGUI() {
        try {
            setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
            pack();
            setSize(400, 300);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void paint(Graphics g) {
        g.drawRect(10, 20, 30, 40);
    }
}

      

        
        
        
      

    

Then I tried using JTextArea

using these two classes, but in this case the rectangle is not displayed at all.

GraphicsEx1.java:

package graphicsex;

import javax.swing.JTextArea;
import java.awt.Graphics;

public class GraphicsEx1 extends javax.swing.JFrame {

    private JTextArea jTextArea1;

    {
        //Set Look & Feel
        try {
            javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        GraphicsEx1 inst = new GraphicsEx1();
        inst.setVisible(true);
    }

    public GraphicsEx1() {
        super();
        initGUI();
    }

    private void initGUI() {
        try {
            setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
            getContentPane().setLayout(null);
            {
                jTextArea1 = new JTextArea();
                getContentPane().add(jTextArea1);
                jTextArea1.setBounds(7, 7, 371, 245);
                jTextArea1.setEnabled(false);
            }
            pack();
            setSize(400, 300);
        } catch (Exception e) {
            e.printStackTrace();
        }
        postInitGUI();
    }

    public void postInitGUI() {
        DisplayItems dp = new DisplayItems();
        jTextArea1 = dp;
        dp.setVisible(true);
        this.add(jTextArea1);
    }
}

      

        
        
        
      

    

And DisplayItems.java:

package graphicsex;

import java.awt.Dimension;
import java.awt.Graphics;

public class DisplayItems extends javax.swing.JTextArea {

    public DisplayItems() {
        super();
        initGUI();
    }

    private void initGUI() {
        try {
            setPreferredSize(new Dimension(400, 300));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void paint(Graphics g) {
        g.drawRect(10, 20, 50, 100);
        g.drawString("Kalai", 90, 150);
    }
}

      

        
        
        
      

    

Can anyone help me to render graphics components on any swinging containers like JFrame,

JPanel or

JTextarea` etc.