Is IntelliJ's java singleton thread-safe

Question

IntelliJ can autogenerate a template for a singleton class, which looks something like this:

public class A {
    private static A ourInstance = new A();

    public static A getInstance() {
        return ourInstance;
    }

    private A() {
    }
}

Is this implementation of singleton thread-safe? I have read about implementing thread-safe singletons through enums. I was wondering if the above implementation is thread-safe as well. As 'ourInstance' has been defined as static and initialized as a class variable, there should be just one copy of the object.

It's published safely, yes. But make the field `final` for good practice. — Sotirios Delimanolis, May 24 '16 at 18:25
you can read this http://stackoverflow.com/questions/70689/what-is-an-efficient-way-to-implement-a-singleton-pattern-in-java — Nicolas Filotto, May 24 '16 at 18:37

score 2 · Accepted Answer · answered May 24 '16 at 18:35

2

You need to add final to your static variable ourInstance to prevent any later modifications then you will have a perfect thread safe singleton.

answered May 24 '16 at 18:35

Nicolas Filotto

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score 1 · Answer 2 · answered May 24 '16 at 18:26

1

Yes, this implementation is thread-safe. Static fields are guaranteed to be initialised and visible before this class or any instance of it are available to the rest of java code.

answered May 24 '16 at 18:26

Nikem

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Is IntelliJ's java singleton thread-safe

2 Answers2