What is a constructor?

A constructor is a "kind of" method in java which is used to initialize objects. The constructor is called when an object of a class is created. It can be used to set initial values for object attributes. A constructor definition is similar to a method definition, except that the constructor should have same name as the class and doesn't contain a return type.

public class MyClass {
    public MyClass() {
      // class level definitions
    }
}

Exploring Java – Understanding ForkJoinPool Framework

A ForkJoinTask is a thread-like entity which is much lighter than a normal thread and can be used to perform huge number of tasks and subtasks at a lower resource cost than a normal Thread implementation. The ForkJoinPool is a collection which hosts a number of such ForkJoinTasks and can take on such heavy lifting tasks.