Java – why can I unexpectedly create multiple instances of my singleton class?

According to my knowledge, singleton design pattern means that we can only create a single object of one class

The following code runs successfully without any errors / exceptions

I want the code to fail because the singletonexample class has a private default constructor

public class SingletonExample {
    private static SingletonExample singletonInstance;

    private SingletonExample() {
    }

    public static SingletonExample getSingletonInstance() {
        if (null == singletonInstance) {
            System.out.println("Creating new instance");
            singletonInstance = new SingletonExample();
        }
        return singletonInstance;
    }

    public void printSingleton(){
        System.out.println("Inside print Singleton");
    }

    public static void main(String a[])  {
        SingletonExample singObj1 = new SingletonExample();
        SingletonExample singObj2 = new SingletonExample();
    }
}

Is there a problem with my code?

Solution

Because your main method is in the class singletonexample, the main code can access the private constructor

Try moving the main method to another class