Add implementation for the Stream API Practice task

src/main/java/practice/CandidateValidator.java

@@ -1,5 +1,20 @@
 package practice;
 
-public class CandidateValidator {
-    //write your code here
+import java.util.function.Predicate;
+import model.Candidate;
+
+public class CandidateValidator implements Predicate<Candidate> {
+    private static final int REQUIRED_YEARS_IN_UKR = 10;
+    private static final int MINIMAL_AGE = 35;
+    private static final String REQUIRED_NATIONALITY = "Ukrainian";
+
+    @Override
+    public boolean test(Candidate candidate) {
+        String[] periodInUkr = candidate.getPeriodsInUkr().split("-");
+        int yearsInUkr = Integer.parseInt(periodInUkr[1]) - Integer.parseInt(periodInUkr[0]);
+        return yearsInUkr >= REQUIRED_YEARS_IN_UKR
+                && candidate.getAge() >= MINIMAL_AGE
+                && candidate.isAllowedToVote()
+                && candidate.getNationality().equals(REQUIRED_NATIONALITY);
+    }
 }

src/main/java/practice/StreamPractice.java

@@ -1,8 +1,12 @@
 package practice;
 
-import java.util.Collections;
+import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import model.Candidate;
+import model.Cat;
 import model.Person;
 
 public class StreamPractice {
@@ -14,16 +18,31 @@ public class StreamPractice {
      * "Can't get min value from list: < Here is our input 'numbers' >"
      */
     public int findMinEvenNumber(List<String> numbers) {
-        return 0;
+        return numbers
+                .stream()
+                .flatMap(s -> Arrays.stream(s.split(",")))
+                .map(Integer::parseInt)
+                .filter(n -> n % 2 == 0)
+                .min(Integer::compareTo)
+                .orElseThrow(() ->
+                        new RuntimeException("Can't get min value from list: " + numbers));
     }
 
     /**
      * Given a List of Integer numbers,
      * return the average of all odd numbers from the list or throw NoSuchElementException.
      * But before that subtract 1 from each element on an odd position (having the odd index).
      */
-    public Double getOddNumsAverage(List<Integer> numbers) {
-        return 0D;
+    public static Double getOddNumsAverage(List<Integer> numbers) {
+        return IntStream.range(0, numbers.size())
+                .map(index -> isOddNumber(index) ? numbers.get(index) - 1 : numbers.get(index))
+                .filter(StreamPractice::isOddNumber)
+                .average()
+                .getAsDouble();
+    }
+
+    private static boolean isOddNumber(int number) {
+        return number % 2 != 0;
     }
 
     /**
@@ -35,7 +54,12 @@ public Double getOddNumsAverage(List<Integer> numbers) {
      * Example: select men who can be recruited to army (from 18 to 27 years old inclusively).
      */
     public List<Person> selectMenByAge(List<Person> peopleList, int fromAge, int toAge) {
-        return Collections.emptyList();
+        return peopleList
+                .stream()
+                .filter(person -> person.getSex().equals(Person.Sex.MAN)
+                        && person.getAge() >= fromAge
+                        && person.getAge() <= toAge)
+                .collect(Collectors.toList());
     }
 
     /**
@@ -50,7 +74,14 @@ public List<Person> selectMenByAge(List<Person> peopleList, int fromAge, int toA
      */
     public List<Person> getWorkablePeople(int fromAge, int femaleToAge,
                                           int maleToAge, List<Person> peopleList) {
-        return Collections.emptyList();
+        return peopleList
+                .stream()
+                .filter(person -> person.getAge() >= fromAge
+                        && (person.getSex().equals(Person.Sex.WOMAN)
+                        && person.getAge() <= femaleToAge
+                        || person.getSex().equals(Person.Sex.MAN)
+                        && person.getAge() <= maleToAge))
+                .collect(Collectors.toList());
     }
 
     /**
@@ -59,7 +90,14 @@ public List<Person> getWorkablePeople(int fromAge, int femaleToAge,
      * return the names of all cats whose owners are women from `femaleAge` years old inclusively.
      */
     public List<String> getCatsNames(List<Person> peopleList, int femaleAge) {
-        return Collections.emptyList();
+        return peopleList
+                .stream()
+                .filter(person -> person.getSex().equals(Person.Sex.WOMAN)
+                        && person.getAge() >= femaleAge)
+                .map(Person::getCats)
+                .flatMap(Collection::stream)
+                .map(Cat::getName)
+                .collect(Collectors.toList());
     }
 
     /**
@@ -75,6 +113,12 @@ public List<String> getCatsNames(List<Person> peopleList, int femaleAge) {
      * parametrized with Candidate in CandidateValidator.
      */
     public List<String> validateCandidates(List<Candidate> candidates) {
-        return Collections.emptyList();
+        CandidateValidator candidateValidator = new CandidateValidator();
+        return candidates
+                .stream()
+                .filter(candidateValidator)
+                .map(Candidate::getName)
+                .sorted()
+                .collect(Collectors.toList());
     }
 }