about enum

[yu yong]

code like this:

enum Animals {DOG, TIGER, CAT}
public class TestEnum {
public static void main(String[] args) {
Animals a = null;
System.out.println(a.DOG);
}
}
The result is : DOG

The question is: In my mind it will cause NullPointException because of the code Animals a = null;
who can tell me why the result comes from. Thanks a lot.

[Ravi Yadav]

Hi,

This is my take on it...
DOG is a static const property of enum Animal.
Animals a = null simply asigned null to the instance of enum.

now a.DOG actually reads the static property of the enum DOG using an instance variable.
Thanks,
Ravi

[yu yong]

Thanks for Ravi.
I think this is the answer.
The code "enum Animals {DOG, TIGER, CAT}" == the code `class Animals{static final String DOG="DOG";static final String TIGER="TIGER";static final String CAT="CAT";}`
If this is currect then the question is clear.

[Darshan Kapadia]

Can You please explain in detail.Since I am still confused that how a "null.Dog" returns Dog.Thanks in advance.

[Irina Goble]

Since I am still confused that how a "null.Dog" returns Dog.Thanks in advance.
The compiler does not look at the reference itself (which is null), it looks at the declared type of the reference (which is Animals).
[ March 24, 2008: Message edited by: Irina Goble ]

[nivriti gunjan]

Since static members of a class can be called using class name also and and enum variables are by default static, using the class type it will call it's variable.