CODEWITHSUNDEEP
javaenums
Abhishek Goel
Abhishek Goel

Reputation: 19731

Assign enum an enums value

I want to assign an enum an enum value like

enum 1

public enum e1{
    value1, 
    value2;
}

enum 2

public enum e2{
    val1 ( some value from e1 ), 
    val2 ( some value from e1 );
}

I should also be able to change the value of val1 later depending on the conditions.

How is that possible in Java?

Upvotes: 0

Views: 488

Answers (4)

johan d
johan d

Reputation: 2863

You can have a member variable in an Enum if you provide a constructor :

    public enum e2{
        A2(e1.B1),
        B2(e1.B1),
        C2(e1.A1);

        e1 e1Value;

        e2(e1 e1NewValue){
            e1Value = e1NewValue;
        }
    }

    public enum e1{
        A1, B1;
    }

Upvotes: 2

rocketboy
rocketboy

Reputation: 9741

Mutable enum, ouch. Technically possible, but i'd advise against it. If its just one time value at the time of intialization, its perfectly fine and good.

public enum e1{
        value1("1"), 
        value2("2");

        String val;
        private e1(String v) {
            val = v;
        }

        //bad don't use
        public void setValue(String v){
            val = v;
        }

        public String getValue(){
            return val;
        }
    }
//usage
e1.value1.setValue("3");
e1.value1.setValue("4");

Upvotes: 1

Joachim Sauer
Joachim Sauer

Reputation: 308001

Enums are basically classes in Java, so you can just make a property:

public enum E2 {
  VAL1(E1.VALUE1),
  VAL2(E2.VALUE2);

  public final E1 e1Value;

  E2(E1 e1Value) {
    this.e1Value = e1Value;
  }
}

You could also make a getter/setter for e1Value, but I'd strongly discourage this. While nothing technically stops you from making a modifyable field in an enum, it is highly unusual and unexpected and will lead to confusing and/or subtle bugs.

Upvotes: 7

Moritz Petersen
Moritz Petersen

Reputation: 13047

You can do something like this:

public enum E1 {
    A, B;
}

and then:

public enum E2 {
    C(E1.A), D(E1.B);

    private final E1 e1;

    private E2(E1 e1) {
        this.e1 = e1;
    }

    public E1 getE1() {
        return e1;
    }
}

Upvotes: 3

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