How to resolve the error : "MyClass.INSTANCE" is not a statement when I try to instantiate a singleton class in Java?

Question

I have a Java Singleton class as :

public enum MyClass{
   INSTANCE;

   private MyClass(){
     init();
   } 

   private static void init(){
     System.out.println("Singleton Class initiated");
   }
}

When I try to instantiate the class by :

MyClass.INSTANCE;

I get an error that it is not a statement.

However, the following works, which is not ideal for production code:

System.out.println(MyClass.INSTANCE);

Is there a way to initiate the enum singleton class properly, without calling any other dummy API of the class?

Just to clarify: you want some code that doesn't actually do anything with your class yet, but that ensures that the class is actually initialized, right? — Joachim Sauer, Nov 12 '18 at 12:03

Ori Marko · Answer 1 · 2018-11-12T14:54:27.220

2

Just state class ( or enum in your case) isn't a valid Java statement.

You can create an object as @Lorelorelore suggested

MyClass instance = MyClass.INSTANCE;

Or if you want to call init() maybe change its signature

public void init(){
    System.out.println("Singleton Class initiated");
}

And call the method directly:

MyClass.INSTANCE.init();

edited Nov 12 '18 at 14:54

answered Nov 12 '18 at 11:55

Ori Marko

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score 1 · Accepted Answer · answered Nov 12 '18 at 13:16

1

As I said in my comment: simply declare it in this way:

MyClass instance = MyClass.INSTANCE;

answered Nov 12 '18 at 13:16

Lorelorelore

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How to resolve the error : "MyClass.INSTANCE" is not a statement when I try to instantiate a singleton class in Java?

2 Answers2