enum constructors

[mark juszczec]

Can someone confirm they can only have default access or private access?

[dennis deems]

http://download.oracle.com/javase/tutorial/java/javaOO/enum.html

The constructor for an enum type must be package-private or private access.

[Matthew Brown]

I think you can declare an enum constructor public, but it doesn't mean you can use it from outside the class - there's a special mechanism for enums that prevents it.

Edit: OK, apparently not . As always, there's only one way to be sure...just tried it out, and it won't compile with a public constructor: "Modifier public not allowed here".

Since you can't create your own enums, a private contructor makes perfect sense. I must admit, I'm not sure why they bother allowing a package-access constructor, but I'm probably missing something.

[mark juszczec]

Dennis Deems wrote:http://download.oracle.com/javase/tutorial/java/javaOO/enum.html

The constructor for an enum type must be package-private or private access.

This got me started fiddling with enum constructor defs.

What the heck is "package-private"?

AFAIK, there's public, protected, default and private.

Is "package-private" a new way to describe on of those?

[Bear Bibeault]

default

[mark juszczec]

Matthew Brown wrote:I think you can declare an enum constructor public, but it doesn't mean you can use it from outside the class - there's a special mechanism for enums that prevents it.

Edit: OK, apparently not . As always, there's only one way to be sure...just tried it out, and it won't compile with a public constructor: "Modifier public not allowed here".

Since you can't create your own enums, a private contructor makes perfect sense. I must admit, I'm not sure why they bother allowing a package-access constructor, but I'm probably missing something.

I tried:

public class EnumTest{

    public enum MyEnum{
	A(1), B(2), C(3);

        int x;

        public  MyEnum(int y){
	    x=y;
	}
    }
}

and got:

bash-3.2$ javac EnumTest.java
EnumTest.java:8: modifier public not allowed here
public MyEnum(int y){
^
1 error

[mark juszczec]

Bear Bibeault wrote:default

so "package-private" means default?

[dennis deems]

mark juszczec wrote:

Bear Bibeault wrote:default

so "package-private" means default?

Yes, but you won't find people using it much. Generally they'll just say "package" or "default". IMO "package-private" is unnecessarily confusing.