singleton with volatile in java

Question

class MyClass
{
      private static volatile Resource resource;

      public static Resource getInstance()
      {
            if(resource == null)
                        


        

Answer 1

I know you aren't asking about better solutions but this is definitely worth if you are looking for a lazy singleton solution.

Use a private static class to load the singleton. The class isn't loaded until invocation and so the reference isn't loaded until the class is. Class loading by implementation is thread-safe and you also incur very little overhead (in case you are doing repetitive volatile loads [which may still be cheap], this resolution always normal loads after initial construction).

class MyClass {
    public static Resource getInstance() {
        return ResourceLoader.RESOURCE;
    }

    private static final class ResourceLoader {
        private static final Resource RESOURCE = new Resource();
    }
}