Golubev Nikita - Part1

src/main/java/data/Generator.java

@@ -60,7 +60,8 @@ public static Employee generateEmployee() {
     }
 
     public static List<Employee> generateEmployeeList() {
-        // TODO
-        throw new UnsupportedOperationException();
+        return Stream.generate(Generator::generateEmployee)
+                .limit(15)
+                .collect(toList());
     }
 }

src/test/java/part1/exercise/StreamsExercise1.java

@@ -1,6 +1,7 @@
 package part1.exercise;
 
 import data.Employee;
+import data.Generator;
 import data.JobHistoryEntry;
 import data.Person;
 import org.junit.Test;
@@ -15,6 +16,7 @@
 import static java.util.stream.Collectors.groupingBy;
 import static java.util.stream.Collectors.mapping;
 import static java.util.stream.Collectors.toList;
+import static org.junit.Assert.assertEquals;
 
 public class StreamsExercise1 {
     // https://youtu.be/kxgo7Y4cdA8 Сергей Куксенко и Алексей Шипилёв — Через тернии к лямбдам, часть 1
@@ -25,14 +27,43 @@ public class StreamsExercise1 {
 
     @Test
     public void getAllEpamEmployees() {
-        List<Person> epamEmployees = null;// TODO all persons with experience in epam
-        throw new UnsupportedOperationException();
+        final List<Employee> employeeList = Generator.generateEmployeeList();
+
+        List<Person> actualPersonList = employeeList.stream()
+                .filter(employee -> employee.getJobHistory().stream()
+                        .map(JobHistoryEntry::getEmployer)
+                        .anyMatch("epam"::equalsIgnoreCase)
+                ).map(Employee::getPerson)
+                .collect(toList());
+
+        List<Person> expectedPersonList = new ArrayList<>();
+        for (Employee employee : employeeList) {
+            for (JobHistoryEntry historyEntry : employee.getJobHistory()) {
+                if (historyEntry.getEmployer().equalsIgnoreCase("epam")) {
+                    expectedPersonList.add(employee.getPerson());
+                    break;
+                }
+            }
+        }
+        assertEquals(actualPersonList, expectedPersonList);
     }
 
     @Test
     public void getEmployeesStartedFromEpam() {
-        List<Person> epamEmployees = null;// TODO all persons with first experience in epam
-        throw new UnsupportedOperationException();
+        final List<Employee> employeeList = Generator.generateEmployeeList();
+        List<Person> epamEmployees = employeeList.stream()
+                .filter(e -> e.getJobHistory().stream().limit(1).collect(toList()).get(0).getEmployer().equals("epam"))
+                .map(Employee::getPerson)
+                .collect(Collectors.toList());
+        List<Person> expectedList = new ArrayList<>();
+
+        for (Employee anEmployeeList : employeeList) {
+            if (anEmployeeList.getJobHistory().get(0).getEmployer().equalsIgnoreCase("epam")) {
+
+                expectedList.add(anEmployeeList.getPerson());
+            }
+        }
+        assertEquals(expectedList, epamEmployees);
     }
 
     @Test
@@ -49,11 +80,12 @@ public void sumEpamDurations() {
             }
         }
 
-        // TODO
-        throw new UnsupportedOperationException();
-
-        // int result = ???
-        // assertEquals(expected, result);
+        final int result = employees.stream()
+                .flatMap(employee -> employee.getJobHistory().stream())
+                .filter(j -> j.getEmployer().equals("epam"))
+                .mapToInt(JobHistoryEntry::getDuration)
+                .sum();
+        assertEquals(expected, result);
     }
 
 }

src/test/java/part1/exercise/StreamsExercise2.java

@@ -1,14 +1,14 @@
 package part1.exercise;
 
 import data.Employee;
+import data.Generator;
 import data.JobHistoryEntry;
 import data.Person;
 import org.junit.Test;
+import part1.example.StreamsExample;
 
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import static data.Generator.generateEmployeeList;
@@ -22,24 +22,111 @@ public class StreamsExercise2 {
     // https://youtu.be/O8oN4KSZEXE Сергей Куксенко — Stream API, часть 1
     // https://youtu.be/i0Jr2l3jrDA Сергей Куксенко — Stream API, часть 2
 
-    // TODO class PersonEmployerPair
+    private static class PersonPositionPair {
+        private final Person person;
+        private final String position;
+
+        public PersonPositionPair(Person person, String position) {
+            this.person = person;
+            this.position = position;
+        }
+
+        public Person getPerson() {
+            return person;
+        }
+
+        public String getPosition() {
+            return position;
+        }
+    }
+
+    private static class PersonEmployerPair {
+
+        private final Person person;
+        private final String employer;
+        private final int duration;
+
+        private PersonEmployerPair(Person person, String employer, int duration) {
+            this.person = person;
+            this.employer = employer;
+            this.duration = duration;
+        }
+
+        public Person getPerson() {
+            return person;
+        }
+
+        public String getEmployer() {
+            return employer;
+        }
+
+        public int getDuration() {
+            return duration;
+        }
+    }
 
     @Test
     public void employersStuffLists() {
-        Map<String, List<Person>> employersStuffLists = null;// TODO
-        throw new UnsupportedOperationException();
+        final List<Employee> employees = Generator.generateEmployeeList();
+
+        Map<String, List<Person>> employersStuffLists = employees.stream()
+                .flatMap(employee -> employee.getJobHistory().stream()
+                        .map(JobHistoryEntry::getPosition)
+                        .map(s -> new PersonPositionPair(employee.getPerson(), s)))
+                .collect(groupingBy(PersonPositionPair::getPosition, mapping(PersonPositionPair::getPerson, toList())));
+
+        Map<String, List<Person>> res = new HashMap<>();
+
+        for (Employee employee : employees) {
+            for (JobHistoryEntry jobHistoryEntry : employee.getJobHistory()) {
+                if (res.containsKey(jobHistoryEntry.getPosition()))
+                    res.get(jobHistoryEntry.getPosition()).add(employee.getPerson());
+                else
+                    res.put(jobHistoryEntry.getPosition(), new ArrayList<>(Collections.singletonList(employee.getPerson())));
+            }
+        }
+
+        assertEquals(res, employersStuffLists);
     }
 
     @Test
     public void indexByFirstEmployer() {
-        Map<String, List<Person>> employeesIndex = null;// TODO
-        throw new UnsupportedOperationException();
+        final List<Employee> employees = Generator.generateEmployeeList();
+
+        Map<String, List<Person>> employeesIndex = employees.stream()
+                .flatMap(employee -> employee.getJobHistory().stream()
+                        .limit(1)
+                        .map(JobHistoryEntry::getPosition)
+                        .map(s -> new PersonPositionPair(employee.getPerson(), s)))
+                .collect(groupingBy(PersonPositionPair::getPosition, mapping(PersonPositionPair::getPerson, toList())));
+
+        Map<String, List<Person>> res = new HashMap<>();
+
+        for (Employee employee : employees) {
+            List<JobHistoryEntry> jobHistory = employee.getJobHistory();
+            for (JobHistoryEntry jobHistoryEntry : jobHistory) {
+                if (res.containsKey(jobHistoryEntry.getPosition()))
+                    res.get(jobHistoryEntry.getPosition()).add(employee.getPerson());
+                else
+                    res.put(jobHistoryEntry.getPosition(), new ArrayList<>(Collections.singletonList(employee.getPerson())));
+                break;
+            }
+        }
+
+        assertEquals(res, employeesIndex);
+
     }
 
     @Test
     public void greatestExperiencePerEmployer() {
-        Map<String, Person> employeesIndex = null;// TODO
+        final List<Employee> employees = getEmployees();
 
+        Map<String, Person> employeesIndex = employees.stream().flatMap(employee -> employee.getJobHistory().stream()
+                .map(j -> new PersonEmployerPair(employee.getPerson(), j.getEmployer(), j.getDuration())))
+                .collect(Collectors.groupingBy(PersonEmployerPair::getEmployer,
+                        Collectors.collectingAndThen(Collectors.maxBy(Comparator.comparingInt(PersonEmployerPair::getDuration)),
+                                p -> p.get().getPerson())
+                ));
         assertEquals(new Person("John", "White", 28), employeesIndex.get("epam"));
     }