[BAEL-6027] Add example for Awaitility and Thread.sleep comparison (#13450)

* Add example for Awaitility and Thread.sleep comparison

* Fix unit test method name and indentation.

* Use property in pom.xml for awaitility dependency version.

---------

Co-authored-by: Uhrin Attila <attila.uhrin@frontendart.com>

core-java-modules/core-java-concurrency-basic-3/pom.xml

@@ -24,4 +24,16 @@
         </resources>
     </build>
 
+    <properties>
+        <awaitility.version>4.2.0</awaitility.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${awaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
 </project>

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

@@ -0,0 +1,35 @@
+package com.baeldung.concurrent;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+import java.util.UUID;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+public class RequestProcessor {
+
+    private Map<String, String> requestStatuses = new HashMap<>();
+
+    public String processRequest() {
+        String requestId = UUID.randomUUID().toString();
+        requestStatuses.put(requestId, "PROCESSING");
+
+        ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor();
+        executorService.schedule((() -> {
+            requestStatuses.put(requestId, "DONE");
+        }), getRandomNumberBetween(500, 2000), TimeUnit.MILLISECONDS);
+
+        return requestId;
+    }
+
+    public String getStatus(String requestId) {
+        return requestStatuses.get(requestId);
+    }
+
+    private int getRandomNumberBetween(int min, int max) {
+        Random random = new Random();
+        return random.nextInt(max - min) + min;
+    }
+}

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

@@ -0,0 +1,41 @@
+package com.baeldung.concurrent;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.not;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.concurrent.TimeUnit;
+
+import org.awaitility.Awaitility;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+@DisplayName("Request processor")
+public class RequestProcessorUnitTest {
+
+    RequestProcessor requestProcessor = new RequestProcessor();
+
+    @Test
+    @DisplayName("Wait for completion using Thread.sleep")
+    void whenWaitingWithThreadSleep_thenStatusIsDone() throws InterruptedException {
+        String requestId = requestProcessor.processRequest();
+
+        Thread.sleep(2000);
+
+        assertEquals("DONE", requestProcessor.getStatus(requestId));
+    }
+
+    @Test
+    @DisplayName("Wait for completion using Awaitility")
+    void whenWaitingWithAwaitility_thenStatusIsDone() {
+        String requestId = requestProcessor.processRequest();
+
+        Awaitility.await()
+          .atMost(2, TimeUnit.SECONDS)
+          .pollDelay(500, TimeUnit.MILLISECONDS)
+          .until(() -> requestProcessor.getStatus(requestId), not(equalTo("PROCESSING")));
+
+        assertEquals("DONE", requestProcessor.getStatus(requestId));
+    }
+
+}