[SOLVED] System exit command is not working properly

I have been staring at this program for a while and can't get it to work. I would appreciate any assistance that you can provide.

Problem: System.exit(0); is not working. IDE gives me an error that I don't understand. System should exit when mouse is pressed inside of rectangle.

Program description: Program is supposed to open drawing window and then draws rectangle. Program loops until mouse is pressed inside of rectangle (Mouse press marked by red hash). System is supposed to close when condition is true.

Code Java:

 
import element.*;  // opens element library
import java.awt.Color;  // opens color library
 
public class DrawHashMarks {  // opens class
 
	/**
	 * This class draws a set of hash marks.  
	* @Walton
	*/
 
	public static void main(String[] args) { //opens main method
 
		DrawingWindow d = new DrawingWindow();   //opens drawing window
		Rect stop = new Rect (50,50,30,30);  // draws rectangle
		Pt pressPoint;  // sets variable for presspoint
 
		d.draw(stop); //a button for stopping 
		d.setForeground(Color.red);  // set color for hash mark 
 
		while (true) { // potentially infinite
 
			pressPoint = d.awaitMousePress(); // mouse is now down
			if (stop.contains(pressPoint));  // leave loop 
			drawHashAt(d,pressPoint); // calls drawHashAt method
			d.awaitMouseRelease();  // mouse is now up
		} // close loop	
 
		System.exit(0);
 
	} // close main method	
 
	public static void drawHashAt (DrawingWindow d, Pt center) { // opens method
	// pre: d is a valid drawing window, center is a valid point 
	// post: draw a hash mark centered at center in drawing window d
 
		d.moveTo(center);  //move to center of hash mark 
		d.move(-10, 0);  //move left 
		d.line(20, 0); //draw horizontal axis 
		d.move(-10, -10); //move up 
		d.line(0, 20); //draw vertical axis
 
	} // opens drawHashAt method 	
 
}  // close class

Thanks for your help. :)