Resolves checkstyle errors for collection-pipeline, command, commander (#1061)

* Reduces checkstyle errors in collection-pipeline

* Reduces checkstyle errors in command

* Reduces checkstyle errors in commander

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/App.java

@@ -23,21 +23,18 @@
 
 package com.iluwatar.collectionpipeline;
 
+import java.util.List;
+import java.util.Map;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.List;
-import java.util.Map;
-
 /**
- * In imperative-style programming, it is common to use for and while loops for
- * most kinds of data processing. Function composition is a simple technique
- * that lets you sequence modular functions to create more complex operations.
- * When you run data through the sequence, you have a collection pipeline.
- * Together, the Function Composition and Collection Pipeline patterns enable
- * you to create sophisticated programs where data flow from upstream to
- * downstream and is passed through a series of transformations.
- *
+ * In imperative-style programming, it is common to use for and while loops for most kinds of data
+ * processing. Function composition is a simple technique that lets you sequence modular functions
+ * to create more complex operations. When you run data through the sequence, you have a collection
+ * pipeline. Together, the Function Composition and Collection Pipeline patterns enable you to
+ * create sophisticated programs where data flow from upstream to downstream and is passed through a
+ * series of transformations.
  */
 public class App {
 
@@ -45,32 +42,35 @@ public class App {
 
   /**
    * Program entry point.
-   * 
-   * @param args
-   *            command line args
+   *
+   * @param args command line args
    */
   public static void main(String[] args) {
 
     List<Car> cars = CarFactory.createCars();
-    
+
     List<String> modelsImperative = ImperativeProgramming.getModelsAfter2000(cars);
     LOGGER.info(modelsImperative.toString());
 
     List<String> modelsFunctional = FunctionalProgramming.getModelsAfter2000(cars);
     LOGGER.info(modelsFunctional.toString());
-    
-    Map<Category, List<Car>> groupingByCategoryImperative = ImperativeProgramming.getGroupingOfCarsByCategory(cars);
+
+    Map<Category, List<Car>> groupingByCategoryImperative =
+        ImperativeProgramming.getGroupingOfCarsByCategory(cars);
     LOGGER.info(groupingByCategoryImperative.toString());
 
-    Map<Category, List<Car>> groupingByCategoryFunctional = FunctionalProgramming.getGroupingOfCarsByCategory(cars);
+    Map<Category, List<Car>> groupingByCategoryFunctional =
+        FunctionalProgramming.getGroupingOfCarsByCategory(cars);
     LOGGER.info(groupingByCategoryFunctional.toString());
-    
+
     Person john = new Person(cars);
 
-    List<Car> sedansOwnedImperative = ImperativeProgramming.getSedanCarsOwnedSortedByDate(List.of(john));
+    List<Car> sedansOwnedImperative =
+        ImperativeProgramming.getSedanCarsOwnedSortedByDate(List.of(john));
     LOGGER.info(sedansOwnedImperative.toString());
 
-    List<Car> sedansOwnedFunctional = FunctionalProgramming.getSedanCarsOwnedSortedByDate(List.of(john));
+    List<Car> sedansOwnedFunctional =
+        FunctionalProgramming.getSedanCarsOwnedSortedByDate(List.of(john));
     LOGGER.info(sedansOwnedFunctional.toString());
   }
 }

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/Car.java

@@ -34,10 +34,11 @@ public class Car {
 
   /**
    * Constructor to create an instance of car.
-   * @param make the make of the car
-   * @param model the model of the car
+   *
+   * @param make       the make of the car
+   * @param model      the model of the car
    * @param yearOfMake the year of built of the car
-   * @param category the {@link Category} of the car
+   * @param category   the {@link Category} of the car
    */
   public Car(String make, String model, int yearOfMake, Category category) {
     this.make = make;
@@ -103,7 +104,7 @@ public class Car {
   public int getYear() {
     return year;
   }
-  
+
   public Category getCategory() {
     return category;
   }

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/CarFactory.java

@@ -34,6 +34,7 @@ public class CarFactory {
 
   /**
    * Factory method to create a {@link List} of {@link Car} instances.
+   *
    * @return {@link List} of {@link Car}
    */
   public static List<Car> createCars() {

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/Category.java

@@ -24,7 +24,7 @@
 package com.iluwatar.collectionpipeline;
 
 /**
- * Enum for the category of car 
+ * Enum for the category of car.
  */
 public enum Category {
   JEEP, SEDAN, CONVERTIBLE

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/FunctionalProgramming.java

@@ -30,20 +30,17 @@ import java.util.stream.Collectors;
 
 /**
  * Iterating and sorting with a collection pipeline
- * 
+ *
  * <p>In functional programming, it's common to sequence complex operations through
- * a series of smaller modular functions or operations. The series is called a
- * composition of functions, or a function composition. When a collection of
- * data flows through a function composition, it becomes a collection pipeline.
- * Function Composition and Collection Pipeline are two design patterns
- * frequently used in functional-style programming.
- * 
+ * a series of smaller modular functions or operations. The series is called a composition of
+ * functions, or a function composition. When a collection of data flows through a function
+ * composition, it becomes a collection pipeline. Function Composition and Collection Pipeline are
+ * two design patterns frequently used in functional-style programming.
+ *
  * <p>Instead of passing a lambda expression to the map method, we passed the
- * method reference Car::getModel. Likewise, instead of passing the lambda
- * expression car -> car.getYear() to the comparing method, we passed the method
- * reference Car::getYear. Method references are short, concise, and expressive.
- * It is best to use them wherever possible.
- * 
+ * method reference Car::getModel. Likewise, instead of passing the lambda expression car ->
+ * car.getYear() to the comparing method, we passed the method reference Car::getYear. Method
+ * references are short, concise, and expressive. It is best to use them wherever possible.
  */
 public class FunctionalProgramming {
   private FunctionalProgramming() {
@@ -51,35 +48,35 @@ public class FunctionalProgramming {
 
   /**
    * Method to get models using for collection pipeline.
-   * 
+   *
    * @param cars {@link List} of {@link Car} to be used for filtering
    * @return {@link List} of {@link String} representing models built after year 2000
    */
   public static List<String> getModelsAfter2000(List<Car> cars) {
     return cars.stream().filter(car -> car.getYear() > 2000)
-      .sorted(Comparator.comparing(Car::getYear))
-      .map(Car::getModel).collect(Collectors.toList());
+        .sorted(Comparator.comparing(Car::getYear))
+        .map(Car::getModel).collect(Collectors.toList());
   }
-  
+
   /**
-   * Method to group cars by category using groupingBy
-   * 
+   * Method to group cars by category using groupingBy.
+   *
    * @param cars {@link List} of {@link Car} to be used for grouping
    * @return {@link Map} with category as key and cars belonging to that category as value
    */
   public static Map<Category, List<Car>> getGroupingOfCarsByCategory(List<Car> cars) {
     return cars.stream().collect(Collectors.groupingBy(Car::getCategory));
   }
-  
+
   /**
-   * Method to get all Sedan cars belonging to a group of persons sorted by year of manufacture 
-   * 
+   * Method to get all Sedan cars belonging to a group of persons sorted by year of manufacture.
+   *
    * @param persons {@link List} of {@link Person} to be used
    * @return {@link List} of {@link Car} to belonging to the group
    */
   public static List<Car> getSedanCarsOwnedSortedByDate(List<Person> persons) {
     return persons.stream().map(Person::getCars).flatMap(List::stream)
-      .filter(car -> Category.SEDAN.equals(car.getCategory()))
-      .sorted(Comparator.comparing(Car::getYear)).collect(Collectors.toList());
+        .filter(car -> Category.SEDAN.equals(car.getCategory()))
+        .sorted(Comparator.comparing(Car::getYear)).collect(Collectors.toList());
   }
 }

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/ImperativeProgramming.java

@@ -31,23 +31,20 @@ import java.util.List;
 import java.util.Map;
 
 /**
- * Imperative-style programming to iterate over the list and get the names of
- * cars made later than the year 2000. We then sort the models in ascending
- * order by year.
- * 
+ * Imperative-style programming to iterate over the list and get the names of cars made later than
+ * the year 2000. We then sort the models in ascending order by year.
+ *
  * <p>As you can see, there's a lot of looping in this code. First, the
- * getModelsAfter2000UsingFor method takes a list of cars as its parameter. It
- * extracts or filters out cars made after the year 2000, putting them into a
- * new list named carsSortedByYear. Next, it sorts that list in ascending order
- * by year-of-make. Finally, it loops through the list carsSortedByYear to get
- * the model names and returns them in a list.
- * 
+ * getModelsAfter2000UsingFor method takes a list of cars as its parameter. It extracts or filters
+ * out cars made after the year 2000, putting them into a new list named carsSortedByYear. Next, it
+ * sorts that list in ascending order by year-of-make. Finally, it loops through the list
+ * carsSortedByYear to get the model names and returns them in a list.
+ *
  * <p>This short example demonstrates what I call the effect of statements. While
- * functions and methods in general can be used as expressions, the {@link Collections}
- * sort method doesn't return a result. Because it is used as a statement, it
- * mutates the list given as argument. Both of the for loops also mutate lists
- * as they iterate. Being statements, that's just how these elements work. As a
- * result, the code contains unnecessary garbage variables
+ * functions and methods in general can be used as expressions, the {@link Collections} sort method
+ * doesn't return a result. Because it is used as a statement, it mutates the list given as
+ * argument. Both of the for loops also mutate lists as they iterate. Being statements, that's just
+ * how these elements work. As a result, the code contains unnecessary garbage variables
  */
 public class ImperativeProgramming {
   private ImperativeProgramming() {
@@ -55,6 +52,7 @@ public class ImperativeProgramming {
 
   /**
    * Method to return the car models built after year 2000 using for loops.
+   *
    * @param cars {@link List} of {@link Car} to iterate over
    * @return {@link List} of {@link String} of car models built after year 2000
    */
@@ -80,16 +78,16 @@ public class ImperativeProgramming {
 
     return models;
   }
-  
+
   /**
-   * Method to group cars by category using for loops
-   * 
+   * Method to group cars by category using for loops.
+   *
    * @param cars {@link List} of {@link Car} to be used for grouping
    * @return {@link Map} with category as key and cars belonging to that category as value
    */
   public static Map<Category, List<Car>> getGroupingOfCarsByCategory(List<Car> cars) {
     Map<Category, List<Car>> groupingByCategory = new HashMap<>();
-    for (Car car: cars) {
+    for (Car car : cars) {
       if (groupingByCategory.containsKey(car.getCategory())) {
         groupingByCategory.get(car.getCategory()).add(car);
       } else {
@@ -100,33 +98,34 @@ public class ImperativeProgramming {
     }
     return groupingByCategory;
   }
-  
+
   /**
-   * Method to get all Sedan cars belonging to a group of persons sorted by year of manufacture using for loops 
-   * 
+   * Method to get all Sedan cars belonging to a group of persons sorted by year of manufacture
+   * using for loops.
+   *
    * @param persons {@link List} of {@link Person} to be used
    * @return {@link List} of {@link Car} to belonging to the group
    */
   public static List<Car> getSedanCarsOwnedSortedByDate(List<Person> persons) {
     List<Car> cars = new ArrayList<>();
-    for (Person person: persons) {
+    for (Person person : persons) {
       cars.addAll(person.getCars());
     }
-  
+
     List<Car> sedanCars = new ArrayList<>();
-    for (Car car: cars) {
+    for (Car car : cars) {
       if (Category.SEDAN.equals(car.getCategory())) {
         sedanCars.add(car);
       }
     }
-  
+
     sedanCars.sort(new Comparator<Car>() {
       @Override
       public int compare(Car o1, Car o2) {
         return o1.getYear() - o2.getYear();
       }
     });
-  
+
     return sedanCars;
   }
 }

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/Person.java

@@ -33,6 +33,7 @@ public class Person {
 
   /**
    * Constructor to create an instance of person.
+   *
    * @param cars the list of cars owned
    */
   public Person(List<Car> cars) {