BAEL-5844: Convert Anonymous Class into Lambda in Java (#13088)

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/anonymousclass/EmailSenderService.java

@@ -0,0 +1,10 @@
+package com.baeldung.anonymousclass;
+
+public class EmailSenderService implements SenderService {
+
+    @Override
+    public String callSender(Sender sender) {
+        return sender.send("Email Notification");
+    }
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/anonymousclass/Sender.java

@@ -0,0 +1,7 @@
+package com.baeldung.anonymousclass;
+
+public interface Sender {
+
+    String send(final String message);
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/anonymousclass/SenderService.java

@@ -0,0 +1,7 @@
+package com.baeldung.anonymousclass;
+
+public interface SenderService {
+
+    String callSender(Sender sender);
+
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/anonymousclass/SmsSenderService.java

@@ -0,0 +1,10 @@
+package com.baeldung.anonymousclass;
+
+public class SmsSenderService implements SenderService {
+
+    @Override
+    public String callSender(Sender sender) {
+        return sender.send("SMS Notification");
+    }
+
+}

core-java-modules/core-java-lambdas/src/test/java/com/baeldung/anonymousclass/AnonymousClassToLambdaIntegrationTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.anonymousclass;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class AnonymousClassToLambdaIntegrationTest {
+
+    @Test
+    public void whenPassingAnonymousClass_thenSuccess() {
+        final SenderService emailSenderService = new EmailSenderService();
+
+        final String emailNotif = emailSenderService.callSender(new Sender() {
+            @Override
+            public String send(String message) {
+                return message;
+            }
+        });
+
+        assertEquals(emailNotif, "Email Notification");
+    }
+
+    @Test
+    public void whenPassingLambdaExpression_thenSuccess() {
+        final SenderService smsSenderService = new SmsSenderService();
+
+        final String smsNotif = smsSenderService.callSender((String message) -> {
+            return message;
+        });
+
+        assertEquals(smsNotif, "SMS Notification");
+    }
+
+}