Java – can I pass parameters to enum values?

Suppose I have an enumeration defined as follows:

public enum Sample{
    // suppose AClass.getValue() returns an int
    A(AClass.getValue()),B(AClass.getValue()),C(AClass.getValue());

    private int _value; 

    private Sample(int _val){
        this._value = _val; 
    }

    public int getVal(){
        return _value; 
    }

I can use sample A or sample A. Getaval () extracts values without problems

Now suppose aclass GetValue () can use parameters to return specific values that may be different, such as aclass getValue(42).

Can I pass parameters to the public enum method and retrieve enumeration values? In other words, I can define it like enum

public enum Sample{
        // suppose AClass.getValue() returns an int
        A(AClass.getAValue()),B(AClass.getBValue()),C(AClass.getCValue());

        private int _value; 

        private Sample(int _val){
           this._value = _val; 
        }

        public int getVal(){
            return _value; 
        }

        public int getVal(int a){
            // somehow pull out AClass.getAValue(a)
        }

Use sample A.getValue(42)？

Solution

You can do this, but you can only create an abstract method in the enumeration and override it in each value:

public enum Sample {
    A(AClass.getAValue()) {
        @Override public int getVal(int x) {
            return AClass.getAValue(x);
        }
    },B(BClass.getAValue()) {
        @Override public int getVal(int x) {
            return BClass.getBValue(x);
        }
    },C(CClass.getAValue()) {
        @Override public int getVal(int x) {
            return CClass.getCValue(x);
        }
    };

    private int _value; 

    private Sample(int _val){
       this._value = _val; 
    }

    public int getVal(){
        return _value; 
    }

    public abstract int getVal(int x);
}

Of course, if you can create an instance of another base type with a getValue (int x) method, you can put the code in the enumeration class itself instead of the nested class