SOS: JPanel ... Help MEEEE!

Question

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class jd extends JPanel implements ActionListener
     int R = 120;
     int T = 120;
     public void paintComponent(Graphics g)
     g.setColor(Color.RED);
     g.drawLine(50,50,R,T);
     g.drawLine(R,T,200,200);
     public void SetupPage()
     JFrame frame = new JFrame("Grrrr");
     frame.setLocationRelativeTo(null);
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     frame.setSize(500,300);
     frame.getContentPane().setLayout(new BorderLayout());
     JButton j = new JButton("abcd");
     frame.add(j);
     j.addActionListener(this);
     frame.getContentPane().add(j, BorderLayout.NORTH);
     JPanel Graph = new jd();
     frame.getContentPane().add(Graph);
     //frame.getContentPane().add(Graph, BorderLayout.SOUTH);
     frame.setVisible(true);
     public static void main(String args[])
          jd J = new jd();
          J.SetupPage();
     public void actionPerformed(ActionEvent e)
                    R = 500;
                    T = 500;
          repaint();
I dont know why... the repaint never works.... and the initial line wont even show if i add the graph to the BorderLayout.SOUTH .. I have to set it to the contentPage ... I am confused.. Help me... Thanks in advance!

Answer 1

You should do the basic tutorials: http://java.sun.com/docs/books/tutorial/uiswing/
Try this code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Jd extends JPanel implements ActionListener{
  int r = 120;
  int t = 120;
  public void paintComponent(Graphics g){
    g.setColor(Color.RED);
    g.drawLine(50, 50, r, t);
    g.drawLine(r, t, 200, 200);
  public static void setupPage(){
    JFrame frame = new JFrame("Grrrr");
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JButton j = new JButton("abcd");
    frame.getContentPane().add(j, BorderLayout.NORTH);
    Jd graph = new Jd();
    frame.getContentPane().add(graph, BorderLayout.CENTER);
    j.addActionListener(graph);
    frame.setSize(500, 500);
    frame.setVisible(true);
  public static void main(String args[]){
    setupPage();
  public void actionPerformed(ActionEvent e){
    r = 500;
    t = 500;
    repaint();
}