Implement Solution

Author: SteffenLm

Exercise.java

@@ -1,6 +1,10 @@
 public class Exercise {
 
   public static void main(String[] args) {
-    // implement exercise here
+    Queries queries = new Queries(DataProvider.getFootballers());
+    queries.getAllFootballersByBirthyear()
+        .values().stream()
+        .forEach(System.out::println);
+    // add more queries as you wish
   }
 }

FootballClub.java

@@ -0,0 +1,4 @@
+
+public record FootballClub(String name, int positionInAllTimeTable, int pointsInAllTimeTable) {
+
+}

Footballer.java

@@ -0,0 +1,6 @@
+import java.time.LocalDate;
+
+public record Footballer(String name, Position position, LocalDate birthDate, int sizeInCm, FootballClub footballClub,
+        int numberOfGames, int numberOfGoals) {
+
+}

Position.java

@@ -0,0 +1,6 @@
+public enum Position {
+    GOALKEEPER,
+    DEFENDER,
+    MIDFIELDER,
+    STRIKER;
+}

Queries.java

@@ -0,0 +1,63 @@
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.OptionalDouble;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+public class Queries {
+
+    private ArrayList<Footballer> footballers;
+
+    public Queries(ArrayList<Footballer> footballers) {
+        this.footballers = footballers;
+    }
+
+    public int getTotalOfAllGoalsByMidfielders() {
+        return footballers.stream()
+                .filter(footballer -> footballer.position().equals(Position.MIDFIELDER))
+                .mapToInt(footballer -> footballer.numberOfGoals())
+                .sum();
+    }
+
+    public Optional<Footballer> getNameOfVfLWolfsburgFootballerWithMostPlayedGames() {
+        Predicate<Footballer> isFromWolfsburg = footballer -> footballer
+                .footballClub().equals(new FootballClub("VfL Wolfsburg", 3, 1145));
+        Comparator<Footballer> sortNumberOfGoalsAscending = (footballer1, footballer2) -> Integer
+                .valueOf(footballer1.numberOfGames()).compareTo(footballer2.numberOfGames());
+
+        return footballers.stream()
+                .filter(isFromWolfsburg)
+                .max(sortNumberOfGoalsAscending);
+    }
+
+    public List<FootballClub> getNameOfAllFootballClubs() {
+        return footballers.stream()
+                .map(footballer -> footballer.footballClub())
+                .distinct()
+                .toList();
+    }
+
+    public boolean isFootballerWithSizeInCmLT170AndNumbreOfGoalsBT0() {
+        return footballers.stream()
+                .anyMatch(footballer -> footballer.sizeInCm() < 170 && footballer.numberOfGoals() > 0);
+    }
+
+    public Map<Integer, List<Footballer>> getAllFootballersByBirthyear() {
+        Function<Footballer, Integer> birthYear = footballer -> footballer.birthDate().getYear();
+        return footballers.stream()
+                .collect(Collectors.groupingBy(birthYear));
+    }
+
+    public  OptionalDouble getAverageNumberOfPointsFromAllBundesligaFootballClubs() {
+        return footballers.stream()
+                .map(footballer -> footballer.footballClub())
+                .distinct()
+                .filter(footballClub -> footballClub.positionInAllTimeTable() != -1)
+                .mapToInt(footballClub -> footballClub.pointsInAllTimeTable())
+                .average();
+    }
+}