Regarding accessing of enum declared inside and outside a class

[Jean John]

Hi,
I found the below code in SCJP book for Java 6 Exam and I have a doubt regarding the comment that enclosing class name is required. I tried without using the enclosing class name and still it works. The jdk i have right now is 1.6

class Coffee2 {
enum CoffeeSize {BIG, HUGE, OVERWHELMING }
CoffeeSize size;
}
public class CoffeeTest2 {
public static void main(String[] args) {
Coffee2 drink = new Coffee2();
drink.size = Coffee2.CoffeeSize.BIG; // enclosing class
// name required
}
}

The book mentions that the syntax for accessing an enum's members depends on where the enum was declared. But even if the enum is declared inside or outside the class, I can access the enum using the same syntax. ie. without enclosing class name. Can someone please bring out some clarity regarding this statement.Thanks.

[Nitesh Nandwana]

Jean John wrote:Hi,
I found the below code in SCJP book for Java 6 Exam and I have a doubt regarding the comment that enclosing class name is required. I tried without using the enclosing class name and still it works. The jdk i have right now is 1.6

class Coffee2 {
enum CoffeeSize {BIG, HUGE, OVERWHELMING }
CoffeeSize size;
}
public class CoffeeTest2 {
public static void main(String[] args) {
Coffee2 drink = new Coffee2();
drink.size = Coffee2.CoffeeSize.BIG; // enclosing class
// name required
}
}

The book mentions that the syntax for accessing an enum's members depends on where the enum was declared. But even if the enum is declared inside or outside the class, I can access the enum using the same syntax. ie. without enclosing class name. Can someone please bring out some clarity regarding this statement.Thanks.

why are you using class name ? that is not right way.It is not matter that enum is declared and defined outside or inside..this'll be correct always

drink.size = CoffeeSize.BIG; 

here you're just assigning one value to size variable from enum named CoffeeSize not from class.

[Jean John]

why are you using class name ? that is not right way.It is not matter that enum is declared and defined outside or inside..this'll be correct always

Please find below the examples about enum in the SCJP Book..

Declaring an enum outside a class:

enum CoffeeSize { BIG, HUGE, OVERWHELMING } // this cannot be
// private or protected
class Coffee {
CoffeeSize size;
}
public class CoffeeTest1 {
public static void main(String[] args) {
Coffee drink = new Coffee();
drink.size = CoffeeSize.BIG; // enum outside class
}
}

The preceding code can be part of a single file. (Remember, the file must be named
CoffeeTest1.java because that's the name of the public class in the file.) The
key point to remember is that an enum that isn't enclosed in a class can be declared
with only the public or default modifier, just like a non-inner class. Here's an
example of declaring an enum inside a class:

class Coffee2 {
enum CoffeeSize {BIG, HUGE, OVERWHELMING }
CoffeeSize size;
}
public class CoffeeTest2 {
public static void main(String[] args) {
Coffee2 drink = new Coffee2();
drink.size = Coffee2.CoffeeSize.BIG; // enclosing class
// name required
}
}

The key points to take away from these examples are that enums can be declared
as their own class, or enclosed in another class, and that the syntax for accessing
an enum's members depends on where the enum was declared.

I have noticed that both methods work and I guess that the book refers to some previous JDK where it was mandatory to access an enum declared inside a Class by usng the enclosing class name . I have tried in JDK 1.6 and both the approach would give the same result

[Prithvi Sehgal]

Dear Jean,

There is something wrong. When an enum is declared outside the class, yes it can be accessed directly and even
from the static context. But when an enum is part of a class, you have to use the enclosing class name, else it won't
compile. Just think logically, how will other class know where the enum is declared so you need to specify the class
name, when an enum is present inside the class.

HTH,

[Jean John]

Hi Prithvi,
I get it now.. The compiler didnt throw an error since I accessed the enum from the same class. I am stupid

package current;

class Ref1 {
	enum CoffeeSize {
		BIG, HUGE, OVERWHELMING
	}

	CoffeeSize size;
}

public class Ref {
	public static void main(String[] args) {
		Ref1 drink = new Ref1();
		drink.size = CoffeeSize.BIG;// Compiler now mentions CoffeeSize can't be resolved..
									
		System.out.println(drink.size);
	}
}

Earlier my code(Code in the Book) was like this.

package current;

public class Ref {

	enum CoffeeSize {
		BIG, HUGE, OVERWHELMING
	}
	CoffeeSize size;
	public static void main(String[] args) {
		Ref drink = new Ref();
		drink.size = CoffeeSize.BIG;//Compiler didn't have an issue since I was accessing a member from the same class..
		System.out.println(drink.size);
	}
}

So no issues with enum and the syntax to access it when it is defined inside a class and outside the class
I am sorry about wasting everyone else's time.. Sorry

[Prithvi Sehgal]

Dear John,

There is a rule over ranch which is NoNeedToSaySorry

Mistakes happen, so it's perfectly fine.

HTH,

[Nitesh Nandwana]

Prithvi Sehgal wrote:Dear Jean,

But when an enum is part of a class, you have to use the enclosing class name, else it won't
compile. Just think logically, how will other class know where the enum is declared so you need to specify the class
name, when an enum is present inside the class.

HTH,

Prithvi i don't think there is need of enclosing class name, enum is inside or outside, it'll never matter as you can see above example.

[Prithvi Sehgal]

Nitesh,

Just look at the code properly. When the enum is inside another class, you need to give the name of the enclosing class.
The case you are talking about is, when enum is outside class or inside same class. We are discussing the case when enum
is part of another class. As the context changes, the using class will never know where that enum is and will complain a compile
time error.

HTH,

[Nitesh Nandwana]

Prithvi Sehgal wrote:Nitesh,

Just look at the code properly. When the enum is inside another class, you need to give the name of the enclosing class.
The case you are talking about is, when enum is outside class or inside same class. We are discussing the case when enum
is part of another class. As the context changes, the using class will never know where that enum is and will complain a compile
time error.

HTH,

Yes sure that'll be absolutely correct, i thought you're talking about above examples.