maybe i did it right?

interfaces-1.iml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_5">
+    <output url="file://$MODULE_DIR$/target/classes" />
+    <output-test url="file://$MODULE_DIR$/target/test-classes" />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/src/test/java" isTestSource="true" />
+      <excludeFolder url="file://$MODULE_DIR$/target" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" scope="TEST" name="Maven: junit:junit:4.12" level="project" />
+    <orderEntry type="library" scope="TEST" name="Maven: org.hamcrest:hamcrest-core:1.3" level="project" />
+  </component>
+</module>

src/main/java/io/zipcoder/interfaces/ConcretePeople.java

@@ -0,0 +1,12 @@
+package io.zipcoder.interfaces;
+
+public class ConcretePeople extends People<Person> {
+
+    public Person[] toArray() {
+        Person[] personArray = new Person[this.count()];
+        for (int i = 0; i < this.count(); i++) {
+            personArray[i] = this.personList.get(i);
+        }
+        return personArray;
+    }
+}

src/main/java/io/zipcoder/interfaces/Educator.java

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+package io.zipcoder.interfaces;
+
+public enum Educator implements Teacher {
+    INSTRUCTOR0(Long.valueOf(1), "instructor0"), INSTRUCTOR1(Long.valueOf(2), "instructor1"), INSTRUCTOR2(Long.valueOf(3), "instructor2"), INSTRUCTOR3(Long.valueOf(4), "instructor3"), INSTRUCTOR4(Long.valueOf(5), "instructor4");
+
+    private Instructor instructor;
+    private Double timeWorked = 0.0;
+
+    Educator (Long id, String name) {
+        this.instructor = new Instructor(id, name);
+    }
+
+    public void teach(Learner learner, Double numberOfHours) {
+        timeWorked += numberOfHours;
+        learner.learn(numberOfHours);
+    }
+
+    public void lecture(Learner[] learners, Double numberOfHours) {
+        Double numberOfHoursPerLearner = numberOfHours / learners.length;
+        for (Learner learner : learners) {
+            teach(learner, numberOfHoursPerLearner);
+        }
+    }
+
+    public Double getTimeWorked() {
+        return timeWorked;
+    }
+
+
+}

src/main/java/io/zipcoder/interfaces/Instructor.java

@@ -0,0 +1,19 @@
+package io.zipcoder.interfaces;
+
+public class Instructor extends Person implements Teacher {
+
+    public Instructor(Long id, String name) {
+        super(id, name);
+
+    }
+    public void teach(Learner learner, Double numberOfHours) {
+        learner.learn(numberOfHours);
+    }
+
+    public void lecture(Learner[] learners, Double numberOfHours) {
+        Double numberOfHoursPerLearner = numberOfHours / learners.length;
+        for (Learner learner: learners) {
+            learner.learn(numberOfHoursPerLearner);
+        }
+    }
+}

src/main/java/io/zipcoder/interfaces/Instructors.java

@@ -0,0 +1,26 @@
+package io.zipcoder.interfaces;
+
+public class Instructors extends People<Instructor> {
+     private static final Instructors INSTANCE;
+
+    private Instructors() {}
+
+    public static Instructors getInstance() {
+        if (INSTANCE == null) {
+            INSTANCE.add(new Instructor(Long.valueOf(3), "Wes"));
+        }
+        return INSTANCE;
+    }
+
+    static {
+        INSTANCE = new Instructors();
+        for (int i = 0; i < 5; i++) {
+            INSTANCE.add(new Instructor(Long.valueOf(i+1), "instructor"+i));
+        }
+
+    }
+
+    public Instructor[] toArray() {
+        return personList.toArray(new Instructor[0]);
+    }
+}

src/main/java/io/zipcoder/interfaces/Learner.java

@@ -0,0 +1,8 @@
+package io.zipcoder.interfaces;
+
+public interface Learner {
+    void learn(Double numberOfHours);
+
+    Double getTotalStudyTime();
+
+}

src/main/java/io/zipcoder/interfaces/People.java

@@ -0,0 +1,67 @@
+package io.zipcoder.interfaces;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+public abstract class People<E extends Person> implements Iterable<E> {
+    List<E> personList = new ArrayList<E>();
+
+    public void add(E person) {
+        this.personList.add(person);
+    }
+
+    public E findById(Long id) {
+        E target = null;
+        for (E person: this.personList) {
+            if (person.getId().equals(id)) {
+                target = person;
+                break;
+            }
+        }
+        return target;
+    }
+
+    public Boolean contains(E person) {
+        Boolean exists = false;
+        for (E eachPerson: this.personList) {
+            if (eachPerson.getName().equals(person.getName())
+                    && eachPerson.getId().equals(person.getId())) {
+                exists = true;
+                break;
+            }
+        }
+        return exists;
+    }
+
+    public void remove(E person) {
+        if (this.contains(person)) {
+            this.personList.remove(person);
+        }
+    }
+
+    public void remove(Long id) {
+        E personToRemove = this.findById(id);
+        this.remove(personToRemove);
+    }
+
+    public void removeAll() {
+        this.personList = new ArrayList<E>();
+    }
+
+    public Integer count() {
+        return this.personList.size();
+    }
+
+    public abstract E[] toArray();
+//        Person[] personArray = new Person[this.count()];
+//        for (int i = 0; i < this.count(); i++) {
+//            personArray[i] = this.personList.get(i);
+//        }
+//        return personArray;
+//    }
+
+    public Iterator<E> iterator() {
+        return personList.iterator();
+    }
+}

src/main/java/io/zipcoder/interfaces/Person.java

@@ -1,5 +1,24 @@
 package io.zipcoder.interfaces;
 
 public class Person {
+    private final long id;
+    private String name;
+
+    public Person(long id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public String getName() {
+        return this.name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
 
 }

src/main/java/io/zipcoder/interfaces/Student.java

@@ -0,0 +1,18 @@
+package io.zipcoder.interfaces;
+
+public class Student extends Person implements Learner {
+    private Double totalStudyTime;
+
+    public Student(Long id, String name) {
+        super(id, name);
+        this.totalStudyTime = 0.0;
+    }
+
+    public void learn(Double numberOfHours) {
+        this.totalStudyTime += numberOfHours;
+    }
+
+    public Double getTotalStudyTime() {
+        return this.totalStudyTime;
+    }
+}

src/main/java/io/zipcoder/interfaces/Students.java

@@ -0,0 +1,25 @@
+package io.zipcoder.interfaces;
+
+public class Students extends People<Student> {
+    private static final Students INSTANCE;
+
+    private Students() {}
+
+    static Students getInstance() {
+        if (INSTANCE == null) {
+            INSTANCE.add(new Student(3L, "Wes"));
+        }
+        return INSTANCE;
+    }
+
+    static {
+        INSTANCE = new Students();
+        for (long i = 0; i < 35; i++) {
+            INSTANCE.add(new Student(i+1L, "student"+i));
+        }
+    }
+
+    public Student[] toArray() {
+        return personList.toArray(new Student[0]);
+    }
+}

src/main/java/io/zipcoder/interfaces/Teacher.java

@@ -0,0 +1,6 @@
+package io.zipcoder.interfaces;
+
+public interface Teacher {
+    void teach(Learner learner, Double numberOfHours);
+    void lecture(Learner[] learners, Double numberOfHours);
+}

src/main/java/io/zipcoder/interfaces/ZipCodeWilmington.java

@@ -0,0 +1,38 @@
+package io.zipcoder.interfaces;
+
+import java.util.LinkedHashMap;
+
+public class ZipCodeWilmington {
+    private static final ZipCodeWilmington INSTANCE = new ZipCodeWilmington();
+
+    private static final Students students = Students.getInstance();
+    private static final Instructors instructors = Instructors.getInstance();
+
+    public static ZipCodeWilmington getInstance() {
+        return INSTANCE;
+    }
+
+    public static void hostLecture (Teacher teacher, Double numberOfHours) {
+        teacher.lecture(students.toArray(), numberOfHours);
+    }
+
+    public static void hostLecture (Long id, Double numberOfHours) {
+        Teacher teacher = instructors.findById(id);
+
+        teacher.lecture(students.toArray(), numberOfHours);
+    }
+
+    public static LinkedHashMap<Student, Double> getStudyMap() {
+        LinkedHashMap<Student, Double> map = new LinkedHashMap<Student, Double>();
+        for (Student student: students) {
+            map.put(student, student.getTotalStudyTime());
+        }
+        return map;
+    }
+
+//    static {
+//        INSTANCE = new ZipCodeWilmington();
+//        students = Students.getInstance();
+//        instructors = Instructors.getInstance();
+//    }
+}

src/test/java/io/zipcoder/interfaces/TestEducator.java

@@ -0,0 +1,39 @@
+package io.zipcoder.interfaces;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class TestEducator {
+
+    @Test
+    public void testTeach() {
+        Student stu = new Student(Long.valueOf(56), "Stu");
+        Educator.INSTRUCTOR1.teach(stu, 5000.0);
+        Assert.assertEquals(stu.getTotalStudyTime(), Educator.INSTRUCTOR1.getTimeWorked(), 2);
+    }
+
+    @Test
+    public void testLecture() {
+        Student stu1 = new Student(Long.valueOf(344), "Stu");
+        Student stu3 = new Student(Long.valueOf(5623), "Stu");
+        Student stu2 = new Student(Long.valueOf(56123), "Stu");
+        Student[] stus = {stu1, stu2, stu3};
+        Educator.INSTRUCTOR2.lecture(stus, 6000.0);
+        Double expected = 2000.0;
+        for (Student stu : stus) {
+            Double actual = stu.getTotalStudyTime();
+            Assert.assertEquals(expected, actual, 2);
+        }
+    }
+
+    @Test
+    public void testGetTimeWorked() {
+        Student stu = new Student(Long.valueOf(333), "Stu");
+        Educator.INSTRUCTOR0.teach(stu, 5000.0);
+        Double actual = Educator.INSTRUCTOR0.getTimeWorked();
+        Double expected = 5000.0;
+        Assert.assertEquals(expected, actual, 2);
+    }
+}

src/test/java/io/zipcoder/interfaces/TestInstructor.java

@@ -0,0 +1,42 @@
+package io.zipcoder.interfaces;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestInstructor {
+    @Test
+    public void testImplementation() {
+        Instructor instructor = new Instructor(Long.valueOf(3), "github");
+        Assert.assertTrue(instructor instanceof Teacher);
+    }
+
+    @Test
+    public void testInheritance() {
+        Instructor instructor = new Instructor(Long.valueOf(3), "github");
+        Assert.assertTrue(instructor instanceof Person);
+    }
+
+    @Test
+    public void testTeach() {
+        Instructor instructor = new Instructor(Long.valueOf(3), "github");
+        Student student1 = new Student(Long.valueOf(5), "Wes");
+        instructor.teach(student1, 45.4);
+        Double actual = student1.getTotalStudyTime();
+        Double expected = 45.4;
+        Assert.assertEquals(expected, actual, 2);
+    }
+
+    @Test
+    public void testLecture() {
+        Instructor instructor = new Instructor(Long.valueOf(3), "github");
+        Student student1 = new Student(Long.valueOf(5), "Wes");
+        Student student2 = new Student(Long.valueOf(8), "Table");
+        Student student3 = new Student(Long.valueOf(33), "Book");
+        Student[] students = {student1, student2, student3};
+
+        instructor.lecture(students, 48.0);
+        for (Student student: students) {
+            Assert.assertEquals(student.getTotalStudyTime(), 16.0, 2);
+        }
+    }
+}