Question

I must be doing something very silly, but I’m getting a ExceptionInInitializerError when I try to instantiate an object in my Singleton:

class MySingleton {

  private static MySingleton instance = null;
  private OtherObject obj;

  // Do I instantiate obj here???
  private MySingleton() {
    //obj = new OtherObject();
  }

  // Or here?
  {
    //obj = new OtherObject();
  }

  // Or where? ...

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

}

Should I make the other object in the constructor, or is that always supposed to be empty for singletons? I get the exception in both the constructor and the initializer block…

Here’s the main():

public static void main(String[] args) {
    try {
        MySingleton singleton = MySingleton.getInstance();
    } catch (Error e) {
        System.err.println("Error!");
    }
}

Answer 1

Static initialization sections are for initializing members of the class marked static. Since OtherObject obj isn’t static it should not be initialized there. The correct place is to initialize it in the constructor.

If you are getting an ExceptionInInitializerError when you have obj = new OtherObject() in the constructor, the problem may be with another class (OtherObject perhaps?) that is incorrectly initializing static members.