First Update

src/main/java/practice/CandidateValidator.java

@@ -1,5 +1,25 @@
 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 MIN_AGE = 35;
+    private static final int MIN_YEARS_IN_UKRAINE = 10;
+    private static final String REQUIRED_NATIONALITY = "Ukrainian";
+    private static final String YEAR_SEPARATOR = "-";
+    private static final int YEAR_FROM_INDEX = 0;
+    private static final int YEAR_TO_INDEX = 1;
+
+    @Override
+    public boolean test(Candidate candidate) {
+        String[] years = candidate.getPeriodsInUkr().split(YEAR_SEPARATOR);
+        int yearsInUkr = Integer.parseInt(years[YEAR_TO_INDEX])
+                - Integer.parseInt(years[YEAR_FROM_INDEX]);
+
+        return candidate.getAge() >= MIN_AGE
+                && candidate.isAllowedToVote()
+                && REQUIRED_NATIONALITY.equals(candidate.getNationality())
+                && yearsInUkr >= MIN_YEARS_IN_UKRAINE;
+    }
 }

src/main/java/practice/StreamPractice.java

@@ -1,8 +1,13 @@
 package practice;
 
-import java.util.Collections;
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 import model.Candidate;
+import model.Cat;
 import model.Person;
 
 public class StreamPractice {
@@ -14,7 +19,13 @@ 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::valueOf)
+                .filter(n -> n % 2 == 0)
+                .min(Comparator.naturalOrder())
+                .orElseThrow(() -> new RuntimeException(
+                        "Can't get min value from list: " + numbers));
     }
 
     /**
@@ -23,34 +34,36 @@ public int findMinEvenNumber(List<String> numbers) {
      * But before that subtract 1 from each element on an odd position (having the odd index).
      */
     public Double getOddNumsAverage(List<Integer> numbers) {
-        return 0D;
+        return IntStream.range(0, numbers.size())
+                .map(i -> i % 2 != 0 ? numbers.get(i) - 1 : numbers.get(i))
+                .filter(n -> n % 2 != 0)
+                .average()
+                .orElseThrow(NoSuchElementException::new);
     }
 
     /**
      * Given a List of `Person` instances (having `name`, `age` and `sex` fields),
-     * for example, `Arrays.asList( new Person(«Victor», 16, Sex.MAN),
-     * new Person(«Helen», 42, Sex.WOMAN))`,
      * select from the List only men whose age is from `fromAge` to `toAge` inclusively.
-     * <p>
-     * 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(p -> p.getSex() == Person.Sex.MAN)
+                .filter(p -> p.getAge() >= fromAge && p.getAge() <= toAge)
+                .collect(Collectors.toList());
     }
 
     /**
      * Given a List of `Person` instances (having `name`, `age` and `sex` fields),
-     * for example, `Arrays.asList( new Person(«Victor», 16, Sex.MAN),
-     * new Person(«Helen», 42, Sex.WOMAN))`,
      * select from the List only people whose age is from `fromAge` and to `maleToAge` (for men)
      * or to `femaleToAge` (for women) inclusively.
-     * <p>
-     * Example: select people of working age
-     * (from 18 y.o. and to 60 y.o. for men and to 55 y.o. for women inclusively).
      */
     public List<Person> getWorkablePeople(int fromAge, int femaleToAge,
                                           int maleToAge, List<Person> peopleList) {
-        return Collections.emptyList();
+        return peopleList.stream()
+                .filter(p -> p.getAge() >= fromAge
+                        && ((p.getSex() == Person.Sex.MAN && p.getAge() <= maleToAge)
+                        || (p.getSex() == Person.Sex.WOMAN && p.getAge() <= femaleToAge)))
+                .collect(Collectors.toList());
     }
 
     /**
@@ -59,22 +72,22 @@ 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(p -> p.getSex() == Person.Sex.WOMAN)
+                .filter(p -> p.getAge() >= femaleAge)
+                .flatMap(p -> p.getCats().stream())
+                .map(Cat::getName)
+                .collect(Collectors.toList());
     }
 
     /**
-     * Your help with a election is needed. Given list of candidates, where each element
-     * has Candidate.class type.
-     * Check which candidates are eligible to apply for president position and return their
-     * names sorted alphabetically.
-     * The requirements are: person should be older than 35 years, should be allowed to vote,
-     * have nationality - 'Ukrainian'
-     * and live in Ukraine for 10 years. For the last requirement use field periodsInUkr,
-     * which has following view: "2002-2015"
-     * We want to reuse our validation in future, so let's write our own impl of Predicate
-     * parametrized with Candidate in CandidateValidator.
+     * Your help with a election is needed.
      */
     public List<String> validateCandidates(List<Candidate> candidates) {
-        return Collections.emptyList();
+        return candidates.stream()
+                .filter(new CandidateValidator())
+                .map(Candidate::getName)
+                .sorted()
+                .collect(Collectors.toList());
     }
 }