null & instanceof

[Akash Singhal]

Hi,

null instance of String  

Returns false

However

 System.out.println(String(null)); 

prints null.

Besides null also gets typecast into any user-defined objects inspite of
instanceof returning false.. how is it possible???Thanking in advance

Regards,

[Abhinay Verma]

null can be cast to any reference type without any side-effects. However, null is never an instance of any class. Therefore,
null instanceof Object will return false

[David Harkness]

The "<reference> instanceof <class>" operator works on the actual instance referred to by <reference>. Since a null reference has no class, it cannot be an instace of any class, and it always returns false.

[ Disabled smilies. ]
[ February 21, 2005: Message edited by: David Harkness ]

[ankur rathi]

System.out.println(String(null));

This will give compile time error . What you want to do ?

[Akash Singhal]

No Rathi,
System.out.println(String(null)) prints null onto the screen.
System.out.println(null) gives compile time error.Please check..

Regards

[Tony Morris]

Rathi is correct.

System.out.println(String(null))

Compile-time error.

System.out.println(null)

Prints literal "null"

Please check.
[ February 21, 2005: Message edited by: Tony Morris ]

[David Harkness]

Originally posted by Akash Singhal:
System.out.println(String(null)) prints null onto the screen.

This is definitely a compile-time error. Do you want to cast the null reference to a String type?

System.out.println((String)null);  // prints "null"

[Paulo Aquino]

 System.out.println((String)null ); 

prints the string null

  System.out.println(null); 

compile time error