Can we declare the constructor static to make a singleton class? java

Question

class SomeClass{
    static SomeClass(){
    }
}

Here, although we maybe able to create different names, but shouldn't it refer to the same memory location? Analogous to calling the same person once by his proper name, once his nickname? Would it still be a singleton class?

A static constructor would not make sense. And why would that make the object a singleton? — OldCurmudgeon, Sep 07 '16 at 19:04
No I know that question is there. I am just thinking about an alternative method for this. — Uddipta_Deuri, Sep 07 '16 at 19:06
Eclipse is giving error on static constructor. Are we not allowed static constructors? — Uddipta_Deuri, Sep 07 '16 at 19:06
A static "constructor" (initializer) looks like this `static { /* do stuff */ }` — Sean Bright, Sep 07 '16 at 19:07
To all the experts here, I can search for the code snippet anywhere. I am asking my own doubt here. If you can't explain this particular doubt, refrain from answering it. — Uddipta_Deuri, Sep 07 '16 at 19:08
If it doesn't compile then obviously it's not an alternative method. Stackoverflow is not a brainstorming session. — Jeroen Vannevel, Sep 07 '16 at 19:08
@SeanBright thanks. A little more elaboration would be appreciated ( if there is any). — Uddipta_Deuri, Sep 07 '16 at 19:09
@MightyPhoenix17, your question and follow up comments do not indicate a sufficient understanding of Java to warrant continued discussion. — Sean Bright, Sep 07 '16 at 19:12

score 2 · Answer 1 · answered Sep 07 '16 at 19:04

You can't have a static constructor as it's job is to initialise a this instance object.

In Scala you can write

object SomeClass {

}

To create something between a singleton and static fields of a class.

The simplest way to define a singleton in Java is to use an enum

enum SomeClass {
    INSTANCE;
}

All references to SomeClass.INSTANCE will be the same instance.

score 1 · Answer 2 · answered Sep 07 '16 at 19:05

This is the correct way to create and publish a singleton, assuming you don't want to use an implicit singleton (like an enum):

public SomeClass
{
    private static class SingletonHolder
    {
        public static final SomeClass INSTANCE = new SomeClass();
    }

    public static SomeClass getInstance()
    {
        return SingletonHolder.INSTANCE;
    }

    private SomeClass()
    {
    }
}

Can we declare the constructor static to make a singleton class? java

2 Answers2