Single instance of an object

Question

Hi,
If wereally want to have one and only one instance of the class we need to do two things.
1. Make the constructor(s) of that class private.
2. Now to create an instance of that class we need to have a public static method in that class. Also take a reffernce variable of the same class.
This method say getInstance() will check the above said reffernce variable and if found null, call the private constructor and assign the object to the reffernce variable. this method then return the instance. If it find the reffernce variable to be not null Then it just return the old object.
Is it thread safe by doing like this. If one thread has created the object of the class and then if that thread is suddenly interupted, then will the second thread create the new object of that class or it picks up the previously created instance only?

Answer 1

Not especially. This is a case where making the thing thread-safe is actually the easier option, anyway. Let the runtime do the heavy lifting
class MySingleton {
   public static final MySingleton INSTANCE = new MySingleton(); // the JVM will lazily load this for you
   private MySingleton() {}There. The runtime will ensure that only one instance (per classloader) will exist