Question

I’ve been trying to program an applet with Netbeans able to draw some graphics into a jPanel, as you can see:
![enter image description here][1]

Applet form:

package Experimento2;

import javax.swing.*;
import java.awt.*;


public class Experimento2 extends javax.swing.JApplet {


    public void init() {
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    initComponents();
                } 
            });
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }


    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        //ZonaGrafica zg = new ZonaGrafica();
        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 466, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 259, Short.MAX_VALUE)
        );

        jButton1.setText("jButton1");

        jButton2.setText("jButton2");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(27, 27, 27)
                .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 175, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 54, Short.MAX_VALUE)
                .addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 187, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(23, 23, 23))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(85, 85, 85)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 61, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 61, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(37, 37, 37))
        );

        //jPanel1.add(zg,BorderLayout.CENTER);
        //zg.repaint();
    }// </editor-fold>


    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JPanel jPanel1;
    // End of variables declaration

}

And the ZonaGrafica class, which is in the same package:

package Experimento2;

import javax.swing.JApplet;
import java.awt.*;

public class ZonaGrafica extends JApplet{

    @Override
    public void paint(Graphics g) {
        super.paint(g);

        g.setColor(Color.red);
        g.fillOval(45, 65, 34, 54);
        g.fillOval(45, 120, 34, 54);
        g.fillOval(45, 180, 34, 54);
    }
}

But unfortunately, nothing happens when I run the jApplet form. In the place where the paint method is supposed to draw some red ovals, nothing is shown. I have no clue to solve this issue, and I would be grateful to whom could help me to solve it..

Answer 1

Don’t override paint. Try with paintComponent instead.

Your ZonaGrafica object is never instantiated(commented). I hope you are at least doing that.

In addition to that, you are trying to ad a JApplet (ZonaGrafica) to another JApplet (Experimento2). Refactor ZonaGrafica and let it extend JPanel or JLabel.