Why can't I get the singleton instance by accessing it directly? [duplicate]

Question

For example:

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

    // Private constructor suppresses
    // default public constructor
    private Singleton() {};

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

Why can't I set the INSTANCE public, and access it by Singleton.INSTANCE? What will it cause?

Answer 1

You technically can and in this code, it will have no effect - it will behave the same.

The reasons we use getters in general are:

• A good habit - people will be surprised to see you access a variable directly
• Flexibility - if you have a hundred places around the code calling the getter, it's easy enough to change the method behavior (like returning new Singleton() every time instead of accessing the static variable). Not so easy if that hundred places access the variable directly.