Difference between recursive task and recursive action in ForkJoinPool

Question

We can submit two types of tasks to forkJoinPool. one is RecursiveAction and other is RecursiveTask.

What is the difference between both of them?

Answer 1

From the first lines of their respective Javadocs:

• [RecursiveTask is] A recursive result-bearing ForkJoinTask.
• [RecursiveAction is] A recursive resultless ForkJoinTask.

Although technically, RecursiveAction does return a value, it's just always null, because it's a ForkJoinTask<Void>, and that's the only possible value of Void.

Answer 2

They are alike except RecursiveTask returns a result while RecursiveAction has no return value.