Why the java method Enum.valueof invoke the enum type constructor?

Question

I have built this kind of data enum:

enum Sexo {
    HOMBRE("H"), MUJER("M"), OTRO("O"); 
    private String sexo;        
    private Sexo(String sexo){ 
        System.out.println("constructor del tipo enum");
        this.sexo=sexo;
    }
 }

Then, in the Main method i just do this:

public static void main(String[] args) {

    Sexo sexo1 = Enum.valueOf(Sexo.class, "HOMBRE"); 
    Sexo sexo2 = Enum.valueOf(Sexo.class, "MUJER"); 
    Sexo.valueOf("OTRO");

}

then, i have this on the console:

constructor del tipo enum
constructor del tipo enum
constructor del tipo enum

i understand that i have a call to the constructor for each enum type whit the sentence "Sexo" (name of the enum type). But: why the constructor is running just once? note that i have two instances and one direct call to the class.

The statement HOMBRE("H"), MUJER("M"), OTRO("O") calls the constructors. Not your valueOf method. — Zabuzard
– Zabuzard, Commented Aug 18, 2018 at 0:33

k5_ · Accepted Answer · 2018-08-18 00:31:27Z

3

It isnt the method valueOf that calls the constructor.

The constructor of an enum is called for every literal when the class is first used. So in your case thats before the first call to Enum.valueOf.

The three calls to the constructor are caused by the three literals not your three calls to valueOf.

answered Aug 18, 2018 at 0:31

k5_

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2 Comments

Zabuzard Over a year ago

@HectorEstigarribia If an answer helped you solve the issue, consider accepting it, thanks.

Hector Estigarribia Over a year ago

sorry.. i accepted the answer with the accept option, thanks

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