Question about Enum Class Qualified

[Cainiao Zou]

I think the enum must be allways used with the enum class qualifier, for example
MyEnum x = MyEnum.ABC // correct
MyEnum x = ABC // incorrect

But there is a exception in switch, the enum must not be qualified there, for example
switch(x) {
case ABC: ... // correct
case MyEnum.ABC: ... // incorrect
}

Is there any other exceptions about the qualified enum?
thanks

[AmanZeeK Verma]

I really liked the question, tried googling it...

Here is one link that has this discussed, I still would like someone to explains this detail...

http://stackoverflow.com/questions/4401743/why-final-static-int-can-be-used-as-a-switchs-case-constant-but-not-final-sta

[Tim McGuire]

This ensures type safety. If you were allowed to qualify the reference, you could not be sure that what you are evaluating is the same as the type you declared in the switch statement. Or, more importantly, the compiler could not be sure.

public enum bird{ CARDINAL, BLUEJAY, CHICKADEE,PIGEON, CROW};
public enum cleric{ POPE, CARDINAL,ARCHBISHOP,PRIEST};
public void doEnumStuff(){
   bird x = bird.CARDINAL;
    cleric x = CARDINAL;  // WRONG.  doesn't know the symbol and if it did, it wouldn't know which enum

}
public checkEnum(bird x){
 switch(x) {
    case PIGEON: ... // correct
           
    case CROW : ... // correct    
    case bird.CARDINAL: ... // incorrect because the compiler sees this as potentially breaking 
//the agreement you made when you switched on x, which has already established x as a bird.  
//It is going "over the head" of the switch statement
 } 

EDIT/JD: code block was too wide

[Javin Paul]

Thanks Tim, though could you please elaborate this line , I think here compiler know the Type of variable x as cleric then what's the problem to assign CARDINAL to it ?

cleric x = CARDINAL; // WRONG. doesn't know the symbol and if it did, it wouldn't know which enum

[Tim McGuire]

If everything in the left-operands type contract can be met through the contract of the right-operand type, then the assignment will work. It doesn't matter if the right-operand type implements more than the left-operand type; as long as it implements what the left-operand type contract guarantees.

"CARDINAL" alone is not recognized period, so the discussion is moot. If it was recognized, without a qualifier to identify the "namespace" of CARDINAL, the right side of the assignment is not living up to the agreement.