How do I implement a thread-safe singleton in Java?

How do I implement a thread-safe singleton in Java?

To implement a thread-safe singleton in Java, you can use the Bill Pugh Singleton Design pattern. This involves using a static inner helper class.

Can you show me an example of that?

Sure! Here's a simple example:

public class Singleton {
    private Singleton() {}

    private static class SingletonHelper {
        private static final Singleton INSTANCE = new Singleton();
    }

    public static Singleton getInstance() {
        return SingletonHelper.INSTANCE;
    }
}

What are the advantages of this approach?

This approach is thread-safe without requiring synchronized blocks, and it also leverages lazy initialization.

Are there any downsides to using this pattern?

One downside is that it may be less intuitive for developers unfamiliar with inner static classes.