Merge pull request #1061 from felipe-gdr/master

BAEL-612: Guide to java.util.concurrent.Future

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();
+    }
+}

core-java/src/main/java/com/baeldung/concurrent/future/SquareCalculator.java

@@ -0,0 +1,24 @@
+package com.baeldung.concurrent.future;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Future;
+
+public class SquareCalculator {
+    
+    private final ExecutorService executor;
+    
+    public SquareCalculator(ExecutorService executor) {
+        this.executor = executor;
+    }
+    
+    public Future<Integer> calculate(Integer input) {        
+        return executor.submit(new Callable<Integer>() {
+            @Override
+            public Integer call() throws Exception {
+                Thread.sleep(1000);
+                return input * input;
+            }
+        });
+    }
+}