Java - passing null as an argument to print()

Question

I want to know why the below code doesn't work :

System.out.print(null);    
response.getWriter().print(null);

But the below ones work :

String s = null;
System.out.print(s);
response.getWriter().print(s);

Whats the difference between passing a null as compared to passing a reference as null ?

EDITED : Doesn't work fore mentioned indicates to compilation error .

Answer 1

This is because you can pass an Object or a String. Since null can fit in both, the compiler doesn't know which method to use, leading to compile error.

Methods definitions:

• System.out.print(Object)
• System.out.print(String)

Instead, if you provide an Object or a String variable (even if it has null value), the compiler would know which method to use.

EDIT: This is better explained in this answer. As to the internal link pointing to the Java specification, you can read it here, and this case would suit here:

The informal intuition is that one method is more specific than another **if any invocation handled by the first method could be passed on to the other one without a compile-time type error.

It is possible that no method is the most specific, because there are two or more methods that are maximally specific.