What restrictions are placed on method overriding?

Below are the listed restrictions:

1. Inherits a method from a superclass
2. Superclass method is not final
3. Superclass method is not private
4. Superclass method is not static
5. Superclass can be abstract
6. Signature must be EXACT SAME
7. Overidden method can not be more restrictive
8. Overidden method must not throw new or broader checked exceptions
9. Call super if overridden
10. The return type must be the same as the original overridden method (or a subtype == covariant returns.)

MethodOverridingDemo.java

abstract class Shape
{
	String res;	
	abstract void area();
	public void disp()
	{
	System.out.println(res);	
	}
}
class Rect extends Shape
{
	public void area() //Overriding area()
	{ res="Rectangle";
	}
}
class Circle extends Shape
{
	public void area() 	//Overriding area()
	{ res="Circle";
	}
}
class MethodOverridingDemo
{
	public static void main(String s[])	
	{
		Rect r=new Rect(); 	r.area();  r.disp();
		Circle c=new Circle(); 	c.area(); c.disp();
		
		//---The same code written as ----------------
		System.out.println("Through Shape class Ref:-");	
		Shape sh=new Rect();
		sh.area();
		sh.disp();
		
		sh=new Circle();
		sh.area();
		sh.disp(); 
		// ---and known as dynamic method dispatch----
}
}