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Re: Overloading methods question

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On Fri, 26 Oct 2018 20:58:44 -0400, Arne Vajhøj wrote:

> On 10/26/2018 3:33 PM, Martin Gregorie wrote:
>> I haven't (so far) used Enums and it wasn't obvious from the tutorial
>> stuff that you can put a public Enum inside a class - rather the
>> opposite in fact, since at one point it said that an enum declaration
>> was at a similar language level to a class declaration,
> 
> It is.
> 
>>                                        which is why I thought it
>> could not be declared inside a class definition.
> 
> You can put a class declaration inside a class.
> 
Yes indeed, but as I found out it seems not so simple to access it from 
outside. The following shows how I wanted to declare and use a enum, i.e. 
as a direct a replacement for the set of public static final ints). 
Here's an SSCCE that shows the problem. 

public class EnumWrapper
{
   public enum MyEnum { ONE, TOO, TREE };

   public static void main(String args[])
   {
      for (MyEnum x: MyEnum.values())
         printVal(x);
   }

   public static void printVal(MyEnum v)
   {
      System.out.println("printval(" + v + ")");
   }      
}

This works as expected with the enum used inside its declaring class:
$ java EnumWrapper
printval(ONE)
printval(TOO)
printval(TREE)
 
BUT, I also want to use it as a parameter when calling a methods in the 
class where the enum is declared, IOW exactly how I'd use a public static 
final int declared in the class:

public class TestRun
{
   public static void main(String args[])
   {
      EnumWrapper ew = new EnumWrapper();

      ew.printval(MyEnum.ONE);
   }
}

... and this won't compile:

This works as expected if the enum is being used inside its declaring 
class:
$ javac TestRun.java 
TestRun.java:7: error: cannot find symbol
      ew.printval(MyEnum.ONE);
                  ^
  symbol:   variable MyEnum
  location: class TestRun
1 error

and, if I replace 'MyEnum' with "EnumWrapper", the name of the class,
it still fails to compile:
$ javac TestRun.java 
TestRun.java:7: error: cannot find symbol
      ew.printval(EnumWrapper.ONE);
                             ^
  symbol:   variable ONE
  location: class EnumWrapper
1 error

Moving the enum to a separate file containing nothing except a package 
name specifier and the public enum declaration obviously works, but is 
not what I want since it separates the constants in the declaration from 
the code that accepts them as method arguments.

I understood, or thought I did, from earlier parts of this thread that it 
should be possible to do what I want, i.e. declare a public enum within 
the class whose methods are controlled by the enum values. I've checked 
various sources on the interwebs including the Oracle tutorial, but 
didn't find anything there, so - what have I missed or misunderstood?


-- 
Martin    | martin at
Gregorie  | gregorie dot org

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Thread

Overloading methods question Rhino <no_offline_contact@example.com> - 2018-10-24 17:04 -0400
  Re: Overloading methods question Arne Vajhøj <arne@vajhoej.dk> - 2018-10-24 18:56 -0400
  Re: Overloading methods question Joerg Meier <joergmmeier@arcor.de> - 2018-10-25 10:13 +0200
    Re: Overloading methods question Rhino <no_offline_contact@example.com> - 2018-10-25 15:53 -0400
      Re: Overloading methods question Eric Douglas <e.d.programmer@gmail.com> - 2018-10-25 13:58 -0700
        Re: Overloading methods question Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-10-25 17:49 -0400
          Re: Overloading methods question Martin Gregorie <martin@mydomain.invalid> - 2018-10-25 22:29 +0000
            Re: Overloading methods question Arne Vajhøj <arne@vajhoej.dk> - 2018-10-25 20:08 -0400
              Re: Overloading methods question Martin Gregorie <martin@mydomain.invalid> - 2018-10-26 00:37 +0000
                Re: Overloading methods question Arne Vajhøj <arne@vajhoej.dk> - 2018-10-25 21:42 -0400
                Re: Overloading methods question Joerg Meier <joergmmeier@arcor.de> - 2018-10-26 12:46 +0200
                Re: Overloading methods question Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-10-26 07:50 -0400
                Re: Overloading methods question Martin Gregorie <martin@mydomain.invalid> - 2018-10-26 19:33 +0000
                Re: Overloading methods question Eric Douglas <e.d.programmer@gmail.com> - 2018-10-26 13:13 -0700
                Re: Overloading methods question Arne Vajhøj <arne@vajhoej.dk> - 2018-10-26 20:58 -0400
                Re: Overloading methods question Martin Gregorie <martin@mydomain.invalid> - 2018-10-27 22:36 +0000
                Re: Overloading methods question Arne Vajhøj <arne@vajhoej.dk> - 2018-10-27 19:38 -0400
                Re: Overloading methods question Martin Gregorie <martin@mydomain.invalid> - 2018-10-28 10:39 +0000
                Re: Overloading methods question Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-10-28 07:54 -0400
          Re: Overloading methods question Eric Douglas <e.d.programmer@gmail.com> - 2018-10-26 06:26 -0700
      Re: Overloading methods question Joerg Meier <joergmmeier@arcor.de> - 2018-10-26 12:52 +0200
        Re: Overloading methods question Rhino <no_offline_contact@example.com> - 2018-10-26 22:10 -0400
          Re: Overloading methods question Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-10-27 07:43 -0400
            Re: Overloading methods question Rhino <no_offline_contact@example.com> - 2018-10-29 14:40 -0400
              Re: Overloading methods question Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-10-29 16:39 -0400
          Re: Overloading methods question Eric Douglas <e.d.programmer@gmail.com> - 2018-10-29 05:07 -0700
            Re: Overloading methods question Rhino <no_offline_contact@example.com> - 2018-10-29 14:41 -0400
  Re: Overloading methods question Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-10-25 07:49 -0400
    Re: Overloading methods question Rhino <no_offline_contact@example.com> - 2018-10-25 16:07 -0400

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