RecursiveTask Java Example
January 08, 2014
compute() in Java RecursiveTask
This is the main method that performs the computation in RecursiveTask .exec() in Java RecursiveTask
exec() returns Boolean values and implements execution conventions.getRawResult() in Java RecursiveTask
This method returns the result which is actually returned by ForkJoinTask.join(). The use of getRawResult() is for debugging only.setRawResult(V value) in Java RecursiveTask
This method forces the arguments value to be returned by getRawResult(). This methd should be used for only this purpose.Fibonacci Number
One good use of RecursiveTask is getting fibonacci number addition . Fibonacci numbers are a series in which the next number is the addition of previous two numbers as below.0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 ...
RecursiveTaskDemo.java
package com.concretepage.util.concurrent;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;
public class RecursiveTaskDemo {
public static void main(String[] args) {
FibonacciCal fibonacciCal = new FibonacciCal(12);
ForkJoinPool pool = new ForkJoinPool();
int i = pool.invoke(fibonacciCal);
System.out.println(i);
}
}
class FibonacciCal extends RecursiveTask<Integer>{
private static final long serialVersionUID = 1L;
final int num;
FibonacciCal(int num) { this.num = num; }
@Override
protected Integer compute() {
if (num <= 1){
return num;
}
FibonacciCal fcal1 = new FibonacciCal(num - 1);
fcal1.fork();
FibonacciCal fcal2 = new FibonacciCal(num - 2);
return fcal2.compute() + fcal1.join();
}
}
