Java quiz. Which statements about the following code are corr

Which statements about the following code are correct ? (in some application):


public class Singleton {
     private static Singleton singleton;
     public static Singleton getInstance() {
          if (singleton == null) {
              singleton = new Singleton();
          }
          return singleton;
     }
}

More then one object of class Singleton can be created in an Application.
Given implementation is not thread-safe.
All calls of method getInstance() will always return the same object.
Given implementation is thread-safe.

Explanation

Many instances of class Singleton can be created - constructor is not private.
Several threads can simultaneously enter the if statement and create several different objects (because synchronization is not used).