stream practice

src/main/java/practice/CandidateValidator.java

@@ -1,5 +1,35 @@
 package practice;
 
-public class CandidateValidator {
-    //write your code here
+import java.util.function.Predicate;
+import model.Candidate;
+/**
+ * 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.
+ */
+
+public class CandidateValidator implements Predicate<Candidate> {
+    private static final int MIN_AGE = 35;
+    private static final String NATIONALITY = "Ukrainian";
+    private static final int PERIOD_IN_UKRAINE = 10;
+    private static final String SEPARATOR = "-";
+
+    @Override
+    public boolean test(Candidate c) {
+        if (c.getAge() < MIN_AGE
+                || !c.isAllowedToVote()
+                || !NATIONALITY.equals(c.getNationality())) {
+            return false;
+        }
+        String[] splitedPeriod = c.getPeriodsInUkr().split(SEPARATOR);
+        int startYear = Integer.parseInt(splitedPeriod[0]);
+        int endYear = Integer.parseInt(splitedPeriod[1]);
+        return (endYear - startYear) >= PERIOD_IN_UKRAINE;
+    }
 }
+
+

src/main/java/practice/StreamPractice.java

@@ -1,80 +1,114 @@
 package practice;
 
-import java.util.Collections;
+import java.util.Arrays;
 import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.function.Predicate;
+import java.util.stream.IntStream;
 import model.Candidate;
+import model.Cat;
 import model.Person;
+import model.Person.Sex;
 
 public class StreamPractice {
+    public static final String SEPARATOR = ",";
+    private final CandidateValidator candidateValidator = new CandidateValidator();
+
     /**
-     * Given list of strings where each element contains 1+ numbers:
-     * input = {"5,30,100", "0,22,7", ...}
-     * return min integer value. One more thing - we're interested in even numbers.
-     * If there is no needed data throw RuntimeException with message
-     * "Can't get min value from list: < Here is our input 'numbers' >"
+     * Given list of strings where each element contains 1+ numbers: input = {"5,30,100", "0,22,7",
+     * ...} return min integer value. One more thing - we're interested in even numbers. If there is
+     * no needed data throw RuntimeException with message "Can't get min value from list: < Here is
+     * our input 'numbers' >"
      */
     public int findMinEvenNumber(List<String> numbers) {
-        return 0;
+        return numbers.stream()
+                .flatMap(n -> Arrays.stream(n.split(SEPARATOR)))
+                .mapToInt(Integer::parseInt)
+                .filter(num -> num % 2 == 0)
+                .min()
+                .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).
+     * 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;
+        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(() -> new NoSuchElementException(
+                        "Didn't find suitable numbers to calculate average"));
     }
 
     /**
-     * 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))`,
+     * 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();
+        Predicate<Person> ageSexFilter = p -> p.getSex() == Sex.MAN
+                && p.getAge() >= fromAge && p.getAge() <= toAge;
+        return peopleList.stream()
+                .filter(Objects::nonNull)
+                .filter(ageSexFilter)
+                .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.
+     * 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).
+     * 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();
+            int maleToAge, List<Person> peopleList) {
+        Predicate<Person> workableFilter = p ->
+                (p.getSex() == Sex.WOMAN && p.getAge() <= femaleToAge)
+                        || (p.getSex() == Sex.MAN && p.getAge() <= maleToAge);
+        return peopleList.stream()
+                .filter(Objects::nonNull)
+                .filter(p -> p.getAge() >= fromAge)
+                .filter(workableFilter)
+                .toList();
     }
 
     /**
-     * Given a List of `Person` instances (having `name`, `age`, `sex` and `cats` fields,
-     * and each `Cat` having a `name` and `age`),
-     * return the names of all cats whose owners are women from `femaleAge` years old inclusively.
+     * Given a List of `Person` instances (having `name`, `age`, `sex` and `cats` fields, and each
+     * `Cat` having a `name` and `age`), 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() == Sex.WOMAN && p.getAge() >= femaleAge)
+                .flatMap(p -> p.getCats().stream())
+                .map(Cat::getName)
+                .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. 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.
      */
     public List<String> validateCandidates(List<Candidate> candidates) {
-        return Collections.emptyList();
+        return candidates.stream()
+                .filter(candidateValidator)
+                .map(Candidate::getName)
+                .sorted()
+                .toList();
     }
 }