From c0756273cacfa831aa05c341834bef41c9107080 Mon Sep 17 00:00:00 2001
From: Felipe Reis <felipe@glr.com.br>
Date: Thu, 26 Jan 2017 17:22:45 -0200
Subject: [PATCH] BAEL-612: Example usage of ForkJoinTask

---
 .../future/FactorialSquareCalculator.java     | 26 +++++++++++++++++++
 .../FactorialSquareCalculatorUnitTest.java    | 22 ++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 core-java/src/main/java/com/baeldung/concurrent/future/FactorialSquareCalculator.java
 create mode 100644 core-java/src/test/java/com/baeldung/concurrent/future/FactorialSquareCalculatorUnitTest.java

diff --git a/core-java/src/main/java/com/baeldung/concurrent/future/FactorialSquareCalculator.java b/core-java/src/main/java/com/baeldung/concurrent/future/FactorialSquareCalculator.java
new file mode 100644
index 0000000000..471072b333
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/concurrent/future/FactorialSquareCalculator.java
@@ -0,0 +1,26 @@
+package com.baeldung.concurrent.future;
+
+import java.util.concurrent.RecursiveTask;
+
+public class FactorialSquareCalculator extends RecursiveTask<Integer> {
+    private static final long serialVersionUID = 1L;
+
+    final private Integer n;
+
+    public FactorialSquareCalculator(Integer n) {
+        this.n = n;
+    }
+
+    @Override
+    protected Integer compute() {
+        if (n <= 1) {
+            return n;
+        }
+
+        FactorialSquareCalculator calculator = new FactorialSquareCalculator(n - 1);
+
+        calculator.fork();
+
+        return n * n + calculator.join();
+    }
+}
diff --git a/core-java/src/test/java/com/baeldung/concurrent/future/FactorialSquareCalculatorUnitTest.java b/core-java/src/test/java/com/baeldung/concurrent/future/FactorialSquareCalculatorUnitTest.java
new file mode 100644
index 0000000000..a47c44506d
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/concurrent/future/FactorialSquareCalculatorUnitTest.java
@@ -0,0 +1,22 @@
+package com.baeldung.concurrent.future;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.concurrent.ForkJoinPool;
+
+import org.junit.Test;
+
+public class FactorialSquareCalculatorUnitTest {
+
+    @Test
+    public void whenCalculatesFactorialSquare_thenReturnCorrectValue() {
+        ForkJoinPool forkJoinPool = new ForkJoinPool();
+
+        FactorialSquareCalculator calculator = new FactorialSquareCalculator(10);
+
+        forkJoinPool.execute(calculator);
+
+        assertEquals("The sum of the squares from 1 to 10 is 385", 385, calculator.join().intValue());
+    }
+
+}