Drawn images do not stay on screen

I am drawing onto a JPanel using getGraphics and the drawLine and fillOval commands but it is very temperamental when running the program. However, when I debug it it draws every time.

draw.drawPoints(drawing.getGraphics(), xCoord, yCoord);

Calls:

public void drawPoints (Graphics g, int x, int y){
    g.setColor(Color.red);
    g.fillOval(x, y, 5, 5);
}

edit: It wont always dra开发者_运维知识库w. Most of the time is stays blank.

I am drawing onto a JPanel using getGraphics

You should not draw stuff on the JPanel by getting a Graphics object from drawing.getGraphics().

Instead, you should override the paintComponent(Graphics g) method and do your painting there.

A simple example to get you started:

container.add(new JPanel() {
    public void paintComponent(Graphics g) {
        drawPoints(g, xCoord, yCoord);
    }
});

You need to do that every time the object is repainted.