RectangleRunner.java

public class RectangleRunner{
   public static void main(String[] args){
      Rectangle def = new Rectangle();
      System.out.println( "This is a default rectangle. I will call its toString by printing this object out" );
      System.out.println( def );
      System.out.println( "Now I will change the values of this default rectangle using mutators");
      def.setLength(3);
      def.setWidth(4);
      System.out.println( def );
      System.out.println("Here is the length alone using its accessor");
      System.out.println( def.getLength() );
      System.out.println("I could create another rectangle using just its specified constructor");
      Rectangle r = new Rectangle(5, 12);
      System.out.println( r );
      System.out.println("Here is this rectangle's diagonal " + r.diagonal() );
   }
}