When you want to divide a graphical program into multiple drawing methods, you must pass Graphics g as a parameter in addition to any other parameters. Example:
public static void main(String[] args) {
DrawingPanel panel = new DrawingPanel(400, 300);
Graphics g = panel.getGraphics();
...
drawStuff(g, 13, 52, 7);
}
public static void drawStuff(Graphics g, int a, int b, int c) {
g.drawLine(a, 45, b, c);
...
}