Review Changes

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

@@ -24,6 +24,7 @@ package com.iluwatar.collectionpipeline;
 
 import java.util.Comparator;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 /**
@@ -53,9 +54,32 @@ public class FunctionalProgramming {
    * @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> getModelsAfter2000UsingPipeline(List<Car> cars) {
+  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());
   }
+  
+  /**
+   * Method to group cars by category using groupingBy
+   * 
+   * @param cars {@link List} of {@link Car} to be used for grouping
+   * @return {@link Map} of {@link String} and {@link List} of {@link Car} with category
+   * as key and cars belonging to that category as value
+   */
+  public static Map<String, 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 
+   * 
+   * @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 -> "Sedan".equals(car.getCategory()))
+      .sorted(Comparator.comparing(Car::getYear)).collect(Collectors.toList());
+  }
 }