Review Changes

collection-pipeline/README.md

@@ -26,4 +26,5 @@ Use the Collection Pipeline pattern when
 ## Credits
 
 * [Function composition and the Collection Pipeline pattern](https://www.ibm.com/developerworks/library/j-java8idioms2/index.html)
-* [Martin Fowler](https://martinfowler.com/articles/collection-pipeline/)
+* [Martin Fowler](https://martinfowler.com/articles/collection-pipeline/)
+* Java8 Streams (https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html)

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

@@ -22,7 +22,9 @@
  */
 package com.iluwatar.collectionpipeline;
 
+import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -49,12 +51,26 @@ public class App {
    */
   public static void main(String[] args) {
 
-    List<Car> cars = Iterating.createCars();
+    List<Car> cars = CarFactory.createCars();
 
-    List<String> modelsImperative = ImperativeProgramming.getModelsAfter2000UsingFor(cars);
+    List<String> modelsImperative = ImperativeProgramming.getModelsAfter2000(cars);
     LOGGER.info(modelsImperative.toString());
 
-    List<String> modelsFunctional = FunctionalProgramming.getModelsAfter2000UsingPipeline(cars);
+    List<String> modelsFunctional = FunctionalProgramming.getModelsAfter2000(cars);
     LOGGER.info(modelsFunctional.toString());
+
+    Map<String, List<Car>> groupingByCategoryImperative = ImperativeProgramming.getGroupingOfCarsByCategory(cars);
+    LOGGER.info(groupingByCategoryImperative.toString());
+
+    Map<String, List<Car>> groupingByCategoryFunctional = FunctionalProgramming.getGroupingOfCarsByCategory(cars);
+    LOGGER.info(groupingByCategoryFunctional.toString());
+
+    Person john = new Person(cars);
+
+    List<Car> sedansOwnedImperative = ImperativeProgramming.getSedanCarsOwnedSortedByDate(Arrays.asList(john));
+    LOGGER.info(sedansOwnedImperative.toString());
+
+    List<Car> sedansOwnedFunctional = FunctionalProgramming.getSedanCarsOwnedSortedByDate(Arrays.asList(john));
+    LOGGER.info(sedansOwnedFunctional.toString());
   }
 }

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

@@ -29,17 +29,19 @@ public class Car {
   private String make;
   private String model;
   private int year;
+  private String category;
 
   /**
    * Constructor to create an instance of car.
-   * @param theMake the make of the car
-   * @param theModel 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
    */
-  public Car(String theMake, String theModel, int yearOfMake) {
-    make = theMake;
-    model = theModel;
-    year = yearOfMake;
+  public Car(String make, String model, int yearOfMake, String category) {
+    this.make = make;
+    this.model = model;
+    this.year = yearOfMake;
+    this.category = category;
   }
 
   public String getMake() {
@@ -53,4 +55,8 @@ public String getModel() {
   public int getYear() {
     return year;
   }
+
+  public String getCategory() {
+    return category;
+  }
 }

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

@@ -28,19 +28,19 @@
 /**
  * A factory class to create a collection of {@link Car} instances.
  */
-public class Iterating {
-  private Iterating() {
+public class CarFactory {
+  private CarFactory() {
   }
 
   /**
    * Factory method to create a {@link List} of {@link Car} instances.
    * @return {@link List} of {@link Car}
    */
   public static List<Car> createCars() {
-    return Arrays.asList(new Car("Jeep", "Wrangler", 2011), new Car("Jeep", "Comanche", 1990),
-        new Car("Dodge", "Avenger", 2010),
-        new Car("Buick", "Cascada", 2016),
-        new Car("Ford", "Focus", 2012),
-        new Car("Chevrolet", "Geo Metro", 1992));
+    return Arrays.asList(new Car("Jeep", "Wrangler", 2011, "Jeep"), new Car("Jeep", "Comanche", 1990, "Jeep"),
+        new Car("Dodge", "Avenger", 2010, "Sedan"),
+        new Car("Buick", "Cascada", 2016, "Convertible"),
+        new Car("Ford", "Focus", 2012, "Sedan"),
+        new Car("Chevrolet", "Geo Metro", 1992, "Convertible"));
   }
 }

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

@@ -24,6 +24,7 @@
 
 import java.util.Comparator;
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 /**
@@ -53,9 +54,32 @@ private 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());
+  }
 }

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

@@ -25,7 +25,9 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 /**
  * Imperative-style programming to iterate over the list and get the names of
@@ -55,7 +57,7 @@ private ImperativeProgramming() {
    * @param cars {@link List} of {@link Car} to iterate over
    * @return {@link List} of {@link String} of car models built after year 2000
    */
-  public static List<String> getModelsAfter2000UsingFor(List<Car> cars) {
+  public static List<String> getModelsAfter2000(List<Car> cars) {
     List<Car> carsSortedByYear = new ArrayList<>();
 
     for (Car car : cars) {
@@ -77,4 +79,54 @@ public int compare(Car car1, Car car2) {
 
     return models;
   }
+
+  /**
+   * Method to group cars by category using for loops
+   * 
+   * @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) {
+    Map<String, List<Car>> groupingByCategory = new HashMap<>();
+    for (Car car: cars) {
+      if (groupingByCategory.containsKey(car.getCategory())) {
+        groupingByCategory.get(car.getCategory()).add(car);
+      } else {
+        List<Car> categoryCars = new ArrayList<>();
+        categoryCars.add(car);
+        groupingByCategory.put(car.getCategory(), categoryCars);
+      }
+    }
+    return groupingByCategory;
+  }
+
+  /**
+   * 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) {
+      cars.addAll(person.getCars());
+    }
+
+    List<Car> sedanCars = new ArrayList<>();
+    for (Car car: cars) {
+      if ("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/test/java/com/iluwatar/collectionpipeline/AppTest.java

@@ -26,6 +26,7 @@
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
@@ -34,17 +35,32 @@
  */
 public class AppTest {
 
-  private List<Car> cars = Iterating.createCars();
+  private List<Car> cars = CarFactory.createCars();
 
   @Test
   public void testGetModelsAfter2000UsingFor() {
-    List<String> models = ImperativeProgramming.getModelsAfter2000UsingFor(cars);
+    List<String> models = ImperativeProgramming.getModelsAfter2000(cars);
     assertEquals(models, Arrays.asList("Avenger", "Wrangler", "Focus", "Cascada"));
   }
 
   @Test
   public void testGetModelsAfter2000UsingPipeline() {
-    List<String> models = FunctionalProgramming.getModelsAfter2000UsingPipeline(cars);
+    List<String> models = FunctionalProgramming.getModelsAfter2000(cars);
     assertEquals(models, Arrays.asList("Avenger", "Wrangler", "Focus", "Cascada"));
   }
+
+  @Test
+  public void testGetGroupingOfCarsByCategory() {
+    Map<String, List<Car>> modelsFunctional = FunctionalProgramming.getGroupingOfCarsByCategory(cars);
+    Map<String, List<Car>> modelsImperative = ImperativeProgramming.getGroupingOfCarsByCategory(cars);
+    assertEquals(modelsFunctional, modelsImperative);
+  }
+
+  @Test
+  public void testGetSedanCarsOwnedSortedByDate() {
+    Person john = new Person(cars);
+    List<Car> modelsFunctional = FunctionalProgramming.getSedanCarsOwnedSortedByDate(Arrays.asList(john));
+    List<Car> modelsImperative = ImperativeProgramming.getSedanCarsOwnedSortedByDate(Arrays.asList(john));
+    assertEquals(modelsFunctional, modelsImperative);
+  }
 }