Singleton Pattern Example

This is a thread safe, lazy load singleton example:

public class Singleton {
    private Singleton() { // make it private to prevent instantiation from outside
        // some code for the constructor
    }

    private static class InsHolder { // Once getInstance() being called, this class will be loaded (Lazy)
        private static final Singleton INSTANCE = new Singleton();
    }

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

The down side of the above code is you can’t throw exceptions on constructor.

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