Lazy field initialization with lambdas

Question

I would like to implement lazy field initialization (or deferred initialization) without an if statement and taking advantage of lambdas. So, I would like to have the same b

Answer 1

You could do something along these lines :

   private Supplier heavy = () -> createAndCacheHeavy();

   public Heavy getHeavy()
   {
      return heavy.get();
   }

   private synchronized Heavy createAndCacheHeavy()
   {
      class HeavyFactory implements Supplier
      {
         private final Heavy heavyInstance = new Heavy();

         public Heavy get()
         {
            return heavyInstance;
         }
      }

      if(!HeavyFactory.class.isInstance(heavy))
      {
         heavy = new HeavyFactory();
      }

      return heavy.get();
   }

I recently saw this as an idea by Venkat Subramaniam. I copied the code from this page.

The basic idea is that the Supplier once called, replaces itself with a simpler factory implementation that returns the initialized instance.

This was in the context of thread safe lazy initialization of a singleton, but you could also apply it to a normal field, obviously.