Simple Bar Graph

Question

What I'm trying to do is make a simple bar graph, with multiple bars of different colors and do this using an array. I create a new bar, set its size and color, and then create another bar, set its size, color and i've also moved it over 10 pixels so its not ontop of the original bar. And I'm using an array for the ractangle shap, and fillrect to fill it.
My problem comes when I add the object to the pane ( frame.getContentPane().add(blue); )
It only adds the last one, it doesn't add the blue bar. does getContentPane repaint the screen or something, so that the previous one doesn't show? Or am I missing something?
Thanks for any input,
Bar Class
import javax.swing.JPanel;
import java.awt.*;
public class Bar extends JPanel
   private int[] xBar = {25, 25, 30, 30};
   private int[] yBar = {350, 100, 100, 350};
     private Color fillColor;
   public Bar()
      setBackground(Color.black);
     public void setSize(int height)
          yBar[1] = height * 10;
          yBar[2] = height * 10;     
     public void changeColor(Color colour)
          fillColor = colour;
     public void moveOver(){
          for(int i = 0; i < xBar.length;i++)
               xBar= xBar[i] + 10;
     // Draws the bar
public void paintComponent(Graphics gc)
super.paintComponent(gc);
gc.setColor(fillColor);
gc.fillPolygon(xBar, yBar, xBar.length); // draw bar
BarChart classimport javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.*;
public class BarChart
// Creates the main frame of the program.
public static void main(String[] args)
JFrame frame = new JFrame("Bar Chart");
          Bar red = new Bar();
          Bar blue = new Bar();
          red.setSize(9);
          red.changeColor(Color.RED);
          blue.moveOver();
          blue.setSize(5);
          blue.changeColor(Color.BLUE);
frame.getContentPane().add(blue);
frame.getContentPane().add(red);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
          frame.setSize(400,400);

Answer 1

Ok, I've recreated the whole thing. And it seems to work well, my only problem now is that the graph seems to move on the x-coordinate randomly each time I recompile and run it. Any idea's on why it may do this? I had a friend look at it, and he said it seems to be calling the draw method multiple times, but I cant figure out how, or why it would even do that. So my question is, why is the graph shifting across the screen each time I compile it and run it?
import javax.swing.JFrame;
import java.io.*;
public class BarGraphDriver
     public static void main(String[] args)
          int[] input = {5, 60, 20, 100};//Set height of each bar in the graph (number between 0 and 10
          JFrame frame = new JFrame("Bar Graph");
          BarPanel panel = new BarPanel(input);
      frame.getContentPane().add(panel);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setVisible(true);     
          frame.setSize(600, 450);
import javax.swing.JPanel;
import java.awt.*;
public class BarPanel extends JPanel
     Bar graph;
   //  Sets up the panel characteristics.
   public BarPanel(int[] values)
          JPanel panel = new JPanel();
          panel.setLayout(null);     
          graph = new Bar(values);     
      setBackground(Color.black);
   //  Draws the bar
     public void paintComponent(Graphics gc)
      super.paintComponent(gc);
          graph.draw(gc);
import javax.swing.JPanel;
import java.awt.*;
public class Bar extends JPanel
   private int[] xBar = {10, 10, 60, 60};
   private int[] yBar = {300, 100, 100, 300};
     private int data[];
     private int origData[];
   public Bar( int initVal[] )
          data = new int[initVal.length];
          origData = new int[initVal.length];
          for(int i=0; i<initVal.length; i++)
               origData[i] = initVal;          
               data[i] = Math.abs(initVal[i] - 300);
public void draw(Graphics gc)
          gc.setColor(Color.RED);
          gc.drawLine(10, 301, 600, 301);//horizontal redline
          gc.drawLine(10, 301, 10, 10);//vertical redline
          for(int h = 0; h<data.length; h++)
               gc.setColor(Color.GRAY);
               gc.drawLine(10, data[h] + 1, 600, data[h] + 1);//horizontal redline
          for (int i=0; i<data.length; i++) //countes each bar
               for (int j=0; j<xBar.length; j++)
                    xBar[j] = xBar[j] + 60;          
               if (data[i] >= 1 || data[i] < yBar.length)
                    for(int k = 1; k < 3; k++){
                         yBar[k] = data[i];
               gc.setColor(Color.BLUE);
          gc.fillPolygon(xBar, yBar, yBar.length); // draw bar
               int xText = xBar[0];
               int yText = data[i] - 10;               
               gc.setColor(Color.WHITE);
               gc.drawString(" " + origData[i], xText, yText);     
Edited by: mark2685 on Oct 31, 2008 12:10 PM
Edited by: mark2685 on Oct 31, 2008 12:14 PM