fishercoder1534
diff --git a/‎src/main/java/multithread/completablefutureexamples/CompletableFutureDemo2.java
Lines changed: 71 additions & 0 deletions b/‎src/main/java/multithread/completablefutureexamples/CompletableFutureDemo2.java
Lines changed: 71 additions & 0 deletions
@@ -0,0 +1,71 @@
+package multithread.completablefutureexamples;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import static multithread.completablefutureexamples.CompletableFutureDemo2.WorkerPool.TIME_FOR_A_COMPUTATION_JOB_IN_MS;
+
+public class CompletableFutureDemo2 {
+
+    private static final int POOL_SIZE = 10;
+    private static final int NUMBER_OF_COMPUTATION_JOBS = 20;
+
+    public static void main(String... args) throws ExecutionException, InterruptedException {
+        System.out.println("Program started.");
+        long start = System.currentTimeMillis();
+        WorkerPool workerPool = new WorkerPool(POOL_SIZE);
+        int finalResult = 0;
+        List<Future<String>> futureList = new ArrayList<>();
+        for (int i = 1; i <= NUMBER_OF_COMPUTATION_JOBS; i++) {
+            Future<String> completableFuture = workerPool.executeAsync(i);
+            futureList.add(completableFuture);
+        }
+        for (Future<String> future : futureList) {
+            String result = future.get();
+            finalResult += Integer.parseInt(result);
+        }
+        long end = System.currentTimeMillis();
+        System.out.println("It took " + (end - start) / 1000
+                + " seconds to complete computation, final result: " + finalResult
+                + ", a total of " + NUMBER_OF_COMPUTATION_JOBS + " computation jobs "
+                + "have been completed, total pool worker size is: " + POOL_SIZE
+                + ", and each job took " + TIME_FOR_A_COMPUTATION_JOB_IN_MS / 1000 + " second(s)."
+        );
+        System.out.println("Program ended.");
+    }
+
+    static class WorkerPool {
+        static final long TIME_FOR_A_COMPUTATION_JOB_IN_MS = 1000l;
+        int poolSize;
+        ExecutorService executorService;
+
+        public WorkerPool(int poolSize) {
+            this.poolSize = poolSize;
+            this.executorService = Executors.newFixedThreadPool(poolSize);
+        }
+
+        public Future<String> executeAsync(int input) {
+            final CompletableFuture completableFuture = new CompletableFuture<>();
+            this.executorService.submit(() -> doWork(completableFuture, input));
+            return completableFuture;
+        }
+
+        private void doWork(CompletableFuture completableFuture, int input) {
+            int result = 0;
+            try {
+                System.out.println(Thread.currentThread().getName() + " is doing some real work now that'll take 1 second to complete.");
+                Thread.sleep(TIME_FOR_A_COMPUTATION_JOB_IN_MS);
+                result += input * 2;
+            } catch (InterruptedException e) {
+                throw new RuntimeException(e);
+            }
+            completableFuture.complete("" + result);
+        }
+    }
+
+}