How to create a singleton class

Question

What is the best/correct way to create a singleton class in java?

One of the implementation I found is using a private constructor and a getInstance() method.

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Answer 1

I will implement singleton in below way.

From Singleton_pattern described by wikiepdia by using Initialization-on-demand holder idiom

This solution is thread-safe without requiring special language constructs (i.e. volatile or synchronized

public final class  LazySingleton {
    private LazySingleton() {}
    public static LazySingleton getInstance() {
        return LazyHolder.INSTANCE;
    }
    private static class LazyHolder {
        private static final LazySingleton INSTANCE = new LazySingleton();
    }
    private Object readResolve()  {
        return LazyHolder.INSTANCE;
    }
}