PaintComponent, paint and repaint?

Question

Hi everybody,
I am a little confused on the usage of these methods. I have two problems:
I have a JPanel inside a Jframe. In order to draw a Line2D object on this panel, I have to overwrite the paintComponent() method of JPanel. This causes two problems for me:
1) If I want to call removeAll() method upon click of a button inside the JPanel, and replace my drawing with something else, paintComponent() method gets called, and repaints my old drawing on the panel again. Meaning it would undo my removeAll() method. How can I have my class not call repaintComponent(), or how can I get rid of this problem.
2) Whenever I move another window on top of the panel, paintComponent gets called, and for some reason, it makes multiple copies of my drawing all over the panel. It looks like whereever I am moving the new window, my drawing gets carried with it!!! This messes my whole drawing. How can I get rid of this?
Thanks all.

Answer 1

Well, I am seeing the same problem even incorporaring your suggestion. Here is my code:
public void paintComponent(Graphics g){
super.paintComponent(g);
Line2D.Double line = null;
Circle parent = null;
Circle child = null;
double x_child;
double x_parent;
double y_child;
double y_parent;
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
// save transform in use
AffineTransform origTx = g2d.getTransform();
ListIterator iterator = globalViewVect.listIterator();
AffineTransform transform = new AffineTransform().getScaleInstance(50f, 50f).getTranslateInstance(10f, 10f);
while(iterator.hasNext()){
GlobalViewInfo gvi = (GlobalViewInfo)iterator.next();
g2d.setPaint(Color.black);
child = gvi.getChild();
parent = gvi.getParent();
x_child = child.getX() % 31 + 10;
y_child = child.getY() % 31 + 10;
if(parent == null) {//If this node is the root
System.out.println("This is the root");
else{
x_parent = parent.getX() % 31 + 10;
y_parent = parent.getY() % 31 + 10;
line = new Line2D.Double(x_parent, y_parent, x_child, y_child);
System.out.println("Line is : " + x_parent + " " + y_parent + " "
+ x_child + " " + y_child + " ");
g2d.setTransform(transform);
g2d.draw(line);
g2d.setPaint(Color.red);
g2d.setFont(new Font("Serif",Font.PLAIN,11)) ;
Circle c = new Circle();
c = child;
c.setX(x_child);
c.setY(y_child);
c.draw(g2d, transform);
g2d.setTransform(origTx);