GUI program help

Question

I'm writing a GUI program that involves drawing several shapes, lines, and images to a JPanel. Some of the shapes need to be dragged around the screen by the user, while others will remain stationary. I can't figure out the overall organization of how the drawing should be done. Some questions are:
1. what type of code should go in the paintComponent method of JPanel?
2. Should the JFrame class implement MouseListener and MouseMotionListener, or should some other class implement these?
3. Will I have to use inner classes? (In my current design, the class that extends JPanel is an inner class of the JFrame class.)
4. How can I minimize flicker when shapes are repainted?

Answer 1

1. what type of code should go in the paintComponent
method of JPanel?Let's say you have a List of all your Shapes:
private List shapes;
public void paintComponent(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    Iterator i = this.shapes.iterator();
    while (i.hasNext()) {
        //Draw your Shape
2. Should the JFrame class implement MouseListener and
MouseMotionListener, or should some other class
implement these?Your pick. I'd have the listeners on your JPanel.
3. Will I have to use inner classes? (In my current
design, the class that extends JPanel is an inner
class of the JFrame class.)Your pick. I prefer using inner classes instead of anonymous classes, but others will say the opposite.
4. How can I minimize flicker when shapes are
repainted?yourPanel.setDoubleBuffered(true);