From 1d289c30b991c4424b7fac1cb1a250dd4e73c921 Mon Sep 17 00:00:00 2001
From: Wynn Teo <49014791+wynnteo@users.noreply.github.com>
Date: Thu, 21 Mar 2024 09:22:00 +0800
Subject: [PATCH] Bael 7641 (#16099)

* BAEL-7490 read write file in separate thread

* Change the to try resources

* Update the code to sync with article

* code demostration for ExecutorService vs CompletableFuture
---
 .../core-java-concurrency-advanced-5/pom.xml  |  4 +-
 .../CompletableFutureDemo.java                | 64 ++++++++++++
 .../ExecutorServiceDemo.java                  | 98 +++++++++++++++++++
 3 files changed, 164 insertions(+), 2 deletions(-)
 create mode 100644 core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/CompletableFutureDemo.java
 create mode 100644 core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/ExecutorServiceDemo.java

diff --git a/core-java-modules/core-java-concurrency-advanced-5/pom.xml b/core-java-modules/core-java-concurrency-advanced-5/pom.xml
index 4f681367e9..9caa943a57 100644
--- a/core-java-modules/core-java-concurrency-advanced-5/pom.xml
+++ b/core-java-modules/core-java-concurrency-advanced-5/pom.xml
@@ -28,8 +28,8 @@
     </build>
 
     <properties>
-        <maven.compiler.source>1.8</maven.compiler.source>
-        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>9</maven.compiler.source>
+        <maven.compiler.target>9</maven.compiler.target>
     </properties>
 
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/CompletableFutureDemo.java b/core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/CompletableFutureDemo.java
new file mode 100644
index 0000000000..b45156db15
--- /dev/null
+++ b/core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/CompletableFutureDemo.java
@@ -0,0 +1,64 @@
+package com.baeldung.executorservicevscompletablefuture;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.TimeUnit;
+
+public class CompletableFutureDemo {
+
+    public static void completableFutureMethod() {
+        CompletableFuture<Integer> future = CompletableFuture.supplyAsync(() -> {
+            return 42;
+        });
+
+        System.out.println(future.join());
+    }
+
+    public static void chainingTaskExample() {
+        CompletableFuture<Integer> firstTask = CompletableFuture.supplyAsync(() -> {
+            return 42;
+        });
+
+        CompletableFuture<String> secondTask = firstTask.thenApply(result -> {
+            return "Result based on Task 1: " + result;
+        });
+
+        System.out.println(secondTask.join());
+    }
+
+    public static void exceptionHandlingExample() {
+        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
+                // Simulate a task that might throw an exception
+                if (true) {
+                    throw new RuntimeException("Something went wrong!");
+                }
+                return "Success";
+            })
+            .exceptionally(ex -> {
+                System.err.println("Error in task: " + ex.getMessage());
+                // Can optionally return a default value
+                return "Error occurred";
+            });
+
+        future.thenAccept(result -> System.out.println("Result: " + result));
+    }
+
+    public static void timeoutExample() {
+        CompletableFuture<String> future = CompletableFuture.supplyAsync(() -> {
+            try {
+                Thread.sleep(5000);
+            } catch (InterruptedException e) {
+                System.err.println("Task execution timed out!");
+            }
+            return "Task completed";
+        });
+
+        CompletableFuture<String> timeoutFuture = future.completeOnTimeout("Timed out!", 2, TimeUnit.SECONDS);
+        String result = timeoutFuture.join();
+        System.out.println("Result: " + result);
+    }
+
+    public static void main(String[] args) {
+        timeoutExample();
+    }
+}
diff --git a/core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/ExecutorServiceDemo.java b/core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/ExecutorServiceDemo.java
new file mode 100644
index 0000000000..99ddea9f2b
--- /dev/null
+++ b/core-java-modules/core-java-concurrency-advanced-5/src/main/java/com/baeldung/executorservicevscompletablefuture/ExecutorServiceDemo.java
@@ -0,0 +1,98 @@
+package com.baeldung.executorservicevscompletablefuture;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+public class ExecutorServiceDemo {
+
+    public static void executorServiceMethod() throws ExecutionException, InterruptedException {
+        ExecutorService executor = Executors.newFixedThreadPool(3);
+        Future<Integer> future = executor.submit(() -> {
+            return 42;
+        });
+
+        System.out.println(future.get());
+    }
+
+    public static void chainingTaskExample() {
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+        Future<Integer> firstTask = executor.submit(() -> {return 42;});
+
+        Future<String> secondTask = executor.submit(() -> {
+            try {
+                Integer result = firstTask.get();
+                return "Result based on Task 1: " + result;
+            } catch (InterruptedException | ExecutionException e) {
+                // Handle exception
+                System.err.println("Error occured: " + e.getMessage());
+            }
+            return null;
+        });
+        executor.shutdown();
+
+        try {
+            // Wait for the second task to complete and retrieve the result
+            String result = secondTask.get();
+            System.out.println(result); // Output: Result based on Task 1: 42
+        } catch (InterruptedException | ExecutionException e) {
+            // Handle exception
+            System.err.println("Error occured: " + e.getMessage());
+        }
+    }
+
+    public static void exceptionHandlingExample() {
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+        Future<String> future = executor.submit(() -> {
+            // Simulate a task that might throw an exception
+            if (true) {
+                throw new RuntimeException("Something went wrong!");
+            }
+            return "Success";
+        });
+
+        try {
+            // This might block the main thread if the task throws an exception
+            String result = future.get();
+            System.out.println("Result: " + result);
+        } catch (InterruptedException | ExecutionException e) {
+            // Handle exceptions thrown by the task or during retrieval
+            System.err.println("Error occured: " + e.getMessage());
+        } finally {
+            executor.shutdown();
+        }
+    }
+
+    public static void timeoutExample() {
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+        Future<String> future = executor.submit(() -> {
+            try {
+                System.out.println("Start");
+                Thread.sleep(5000);
+                System.out.println("End");
+            } catch (InterruptedException e) {
+                System.err.println("Error occured: " + e.getMessage());
+            }
+            return "Task completed";
+        });
+
+        try {
+            String result = future.get(2, TimeUnit.SECONDS);
+            System.out.println("Result: " + result);
+        } catch (TimeoutException e) {
+            System.err.println("Task execution timed out!");
+            future.cancel(true);
+        } catch (Exception e) {
+            System.err.println("Error occured: " + e.getMessage());
+        } finally {
+            executor.shutdown();
+        }
+    }
+
+    public static void main(String[] args) throws ExecutionException, InterruptedException {
+        timeoutExample();
+    }
+}