Easy swing question for Java friends

Question

Hi could somebody test this short application and tell me why the "DRAW LINE" button doesnt draw a line as I expected?
thank you very much!
Circuitos.java:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.URL;
import java.awt.geom.*;
public class Circuitos extends JApplet {
     protected JButton btnRect;
     protected Terreno terreno;
     private boolean inAnApplet = true;
     //Hack to avoid ugly message about system event access check.
     public Circuitos() {
          this(true);
     public Circuitos(boolean inAnApplet) {
        this.inAnApplet = inAnApplet;
          if (inAnApplet) {
               getRootPane().putClientProperty("defeatSystemEventQueueCheck",Boolean.TRUE);
     public void init() {
          setContentPane(makeContentPane());
     public Container makeContentPane() {
          btnRect = new JButton("DRAW LINE");
      btnRect.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            terreno.pintarTramo();
          terreno = new Terreno();
          JPanel panel = new JPanel();
          panel.setLayout(new BorderLayout());
          panel.add("North",btnRect);
          panel.add("Center",terreno);
          return panel;
     public static void main(String[] args) {
        JFrame frame = new JFrame("Dise�o de Circuitos");
          frame.addWindowListener(new WindowAdapter() {
               public void windowClosing(WindowEvent e) {
                    System.exit(0);
          Circuitos applet = new Circuitos(false);
          frame.setContentPane(applet.makeContentPane());
          frame.pack();
          frame.setVisible(true);
}Terreno.java:
import java.awt.*;
import javax.swing.*;
import java.awt.geom.*;
public class Terreno extends JPanel {
     Graphics2D g2;
     public Terreno() {
          setBackground(Color.red);
          setPreferredSize(new Dimension(500,500));
     public void paintComponent(Graphics g) {
          super.paintComponent(g);
      g2 = (Graphics2D) g;
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);    
     public void pintarTramo () {     
          Point2D.Double start   = new Point2D.Double(250,250);
          Point2D.Double end     = new Point2D.Double(250,285);
          g2.draw(new Line2D.Double(start,end));            
}

Answer 1

I don't think the date I became a member has anything to do with it. Yes, I signed up a year ago to ask a question or two when I didn't know anything. It wasn't until recently have I started to use this forum again, only to try and help people as well as ask my questions. It took me a year to get to this point to where I can actually answer questions instead of just asking. So don't be silly and judge a person based on their profile.
Secondly, I agree with you, the search utility is great. I use it all the time and usually I'll find my answers, but if I don't is it such a pain in the butt for you to see the same problem posted again?? I know how much you want people to use the resources available before wasting forum space with duplicate questions, but it's not going to happen. Some people are not as patient and you being a butt about it won't stop it.
My point in general is that there are nice ways to help people and even rude ways, and your comments at times come across rude to me, even condescending. You have a lot of knowledge, therefore certain things seem trivial to you... but try to understand where some of the new people are coming from. The Swing tutorial is extremely helpful but if you don't understand the concept of programming or java that well... then it can be overwhelming and you don't know where to start. It's a huge tutorial and when people are stuck they just want an answer to their one question. Most figure it's easier to ask someone who already knows instead of reading an entire tutorial to get their answer.
I've learned by both methods, by taking the time to research it myself and by asking a lot of questions. I have the time. Some don't. Please realize that not everyone is like you and they will continue to ask whether you like it or not. You have a choice, either help them or not.