Problems changing colour using Graphics class in java.awt

Question

Hi,
The problem only happens when more than two images are on a panel. In this case, I have to strings that are drawn. The first drawn string is called "A" the second drawn string is called "B". However, when i change the colour of "B" to let's say Red, the panel erases the letter "B" and insteads changes "A" to red. How can I fix this so that when the user chooses the colour red it changes the colour of the latest drawn string and not the first one. please help!!!!
import java.awt.*;
public class StringPanel extends GBPanel
     private String shape = "clear", str;
     private int x, y;
     private Color color = Color.black;
     public void paintComponent(Graphics g)
          super.paintComponent(g);
          g.setColor (color);
          if(shape.equalsIgnoreCase("draw string"))
               g.setColor(color);
               g.drawString(str, x, y);
          else if (shape.equalsIgnoreCase("exit"))
               System.exit(0);
     public void drawCurve(Color color)
     this.color = color;
     repaint();
     public void drawString(String shape, String str, int x, int y)
          this.shape = shape;
          this.str = str;
          this.x = x;
          this.y = y;
          repaint();
     public void drawString1(String shape, String str, int x, int y)
          Graphics g = getGraphics();
          g.setColor(color);
          if (shape.equalsIgnoreCase("draw string"))
               g.setColor(color);
               g.drawString(str, x, y);
          else
               repaint();
}

Answer 1

well, as I said, I can't remember what the update method thing was for... I think it was related to not clearing the screen first.
Anyway, if you maintain a list of objects that should be drawn and then in the paintComponent method, loop thru the list of objects and redraw them, it will work. Then you change the state of an object and call repaint. When you are going to change color, you need to, in effect, redraw the entire affected area. Now this can be done partially with clipping, but it's complicated to deal with that. So the simplest way is just redraw everything on repaint.