Simple Technique: How to implement @Singleton annotation in a class

If the class has @Singleton annotation, then your purpose would not solved.

@Singleton
public class MyClass { 

// Code

}

Because no annotation can prevent a class having public contructor being instantiated.

Just use following technique to your class being instantiated at most once 

in an application.

public class MyClass {
    private static MyClass instance = null;

    private MyClass() {
    }
    
    public static MyClass getInstance()
    {
        if(instance == null)
        {
            instance = new MyClass();
        }
        return instance;
    }
}