The Task class you implemented in this recipe processes an array of numbers. It checks if the block of numbers it has to process has 10 or more elements. In that case, it splits the block in two and creates two new Task objects to process those blocks. Otherwise, it looks for the element in the fourth position of the array (index number three). If that element is in the block the task has to process, it throws RuntimeException.
When you execute the program, the exception is thrown, but the program doesn't stop. In the Main class you have included a call to the isCompletedAbnormally() method of the ForkJoinTask class using the original task. This method returns true if that task, or one of its subtasks, has thrown an exception. ...
