https://github.com/iluwatar/java-design-patterns/issues/1021 - decrease number of checkstyle errors in callback pattern (#1053)

callback/src/main/java/com/iluwatar/callback/App.java

@@ -24,23 +24,27 @@
 package com.iluwatar.callback;
 
 import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+
+import static org.slf4j.LoggerFactory.getLogger;
 
 /**
- * 
- * Callback pattern is more native for functional languages where functions are treated as
- * first-class citizens. Prior to Java 8 callbacks can be simulated using simple (alike command)
- * interfaces.
- * 
+ *
+ * Callback pattern is more native for functional languages where functions are
+ * treated as first-class citizens. Prior to Java 8 callbacks can be simulated
+ * using simple (alike command) interfaces.
+ *
  */
-public class App {
+public final class App {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+  private static final Logger LOGGER = getLogger(App.class);
+
+  private App() {
+  }
 
   /**
    * Program entry point
    */
-  public static void main(String[] args) {
+  public static void main(final String[] args) {
     Task task = new SimpleTask();
     Callback callback = () -> LOGGER.info("I'm done now.");
     task.executeWith(callback);

callback/src/main/java/com/iluwatar/callback/Callback.java

@@ -24,9 +24,9 @@
 package com.iluwatar.callback;
 
 /**
- * 
+ *
  * Callback interface
- * 
+ *
  */
 public interface Callback {
 

callback/src/main/java/com/iluwatar/callback/LambdasApp.java

@@ -24,22 +24,25 @@
 package com.iluwatar.callback;
 
 import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+
+import static org.slf4j.LoggerFactory.getLogger;
 
 /**
  *
- * This example generates the exact same output as {@link App} however the callback has been
- * defined as a Lambdas expression.
+ * This example generates the exact same output as {@link App} however the
+ * callback has been defined as a Lambdas expression.
  *
  */
-public class LambdasApp {
+public final class LambdasApp {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(LambdasApp.class);
+  private static final Logger LOGGER = getLogger(LambdasApp.class);
+
+  private LambdasApp() { }
 
   /**
    * Program entry point
    */
-  public static void main(String[] args) {
+  public static void main(final String[] args) {
     Task task = new SimpleTask();
     Callback c = () -> LOGGER.info("I'm done now.");
     task.executeWith(c);

callback/src/main/java/com/iluwatar/callback/SimpleTask.java

@@ -24,19 +24,21 @@
 package com.iluwatar.callback;
 
 import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
+
+import static org.slf4j.LoggerFactory.getLogger;
 
 /**
- * 
+ *
  * Implementation of task that need to be executed
- * 
+ *
  */
-public class SimpleTask extends Task {
+public final class SimpleTask extends Task {
 
-  private static final Logger LOGGER = LoggerFactory.getLogger(SimpleTask.class);
+  private static final Logger LOGGER = getLogger(SimpleTask.class);
 
   @Override
   public void execute() {
-    LOGGER.info("Perform some important activity and after call the callback method.");
+    LOGGER.info("Perform some important activity and after call the"
+            + " callback method.");
   }
 }

callback/src/main/java/com/iluwatar/callback/Task.java

@@ -24,16 +24,16 @@
 package com.iluwatar.callback;
 
 /**
- * 
+ *
  * Template-method class for callback hook execution
- * 
+ *
  */
 public abstract class Task {
 
   /**
    * Execute with callback
    */
-  public final void executeWith(Callback callback) {
+  final void executeWith(final Callback callback) {
     execute();
     if (callback != null) {
       callback.call();

callback/src/main/java/com/iluwatar/callback/package-info.java

@@ -0,0 +1 @@
+package com.iluwatar.callback;