BAEL-5814 - Is CompletableFuture Non-blocking (#13917)

* BAEL-5814 - Is CompletableFuture Non-blocking

* Fix the formatting

core-java-modules/core-java-concurrency-basic-3/src/main/java/com/baeldung/concurrent/completablefuture/NonBlockingExample.java

@@ -0,0 +1,17 @@
+package com.baeldung.concurrent.completablefuture;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.CompletableFuture;
+
+public class NonBlockingExample {
+
+    private static final Logger logger = LoggerFactory.getLogger(NonBlockingExample.class);
+
+    public static void main(String[] args) {
+        CompletableFuture.supplyAsync(() -> "Baeldung")
+          .thenApply(String::length)
+          .thenAccept(s -> logger.info(String.valueOf(s)));
+    }
+}

core-java-modules/core-java-concurrency-basic-3/src/test/java/com/baeldung/concurrent/completablefuture/BlockingUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.concurrent.completablefuture;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class BlockingUnitTest {
+
+    @Test
+    void givenCompletableFuture_whenGet_thenReturnResult()
+      throws ExecutionException, InterruptedException {
+        CompletableFuture<String> completableFuture = CompletableFuture
+          .supplyAsync(() -> "Baeldung")
+          .thenApply(String::toUpperCase);
+
+        assertEquals("BAELDUNG", completableFuture.get());
+    }
+
+    @Test
+    void givenCompletableFuture_whenJoin_thenReturnResult() {
+        CompletableFuture<String> completableFuture = CompletableFuture
+          .supplyAsync(() -> "Blocking")
+          .thenApply(s -> s + " Operation")
+          .thenApply(String::toLowerCase);
+
+        assertEquals("blocking operation", completableFuture.join());
+    }
+}