added play-framework project (#678)

* made changes to java reflection

* removed redundant method makeSound in Animal abstract class

* added project for play-framework article

play-framework/student-api/app/models/Student.java

@@ -0,0 +1,47 @@
+package models;
+public class Student {
+    private String firstName;
+    private String lastName;
+    private int age;
+    private int id;
+	public Student(){}
+    public Student(String firstName, String lastName, int age) {
+        super();
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.age = age;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+}

play-framework/student-api/app/models/StudentStore.java

@@ -0,0 +1,52 @@
+package models;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class StudentStore {
+    private static StudentStore instance;
+    private Map<Integer, Student> students = new HashMap<>();
+
+    public static StudentStore getInstance() {
+        if (instance == null)
+            instance = new StudentStore();
+        return instance;
+    }
+
+    public Student addStudent(Student student) {
+        int id = students.size() + 1;
+        student.setId(id);
+        students.put(id, student);
+        return student;
+    }
+
+    public Student getStudent(int id) {
+        if (students.containsKey(id))
+            return students.get(id);
+        return null;
+    }
+
+    public List<Student> getAllStudents() {
+        return new ArrayList<Student>(students.values());
+    }
+
+    public Student updateStudent(Student student) {
+		int id=student.getId();
+        if (students.containsKey(id)) {
+            student.setId(id);
+            students.put(id, student);
+            return student;
+        }
+        return null;
+    }
+
+    public boolean deleteStudent(int id) {
+
+        if (!students.containsKey(id))
+            return false;
+        students.remove(id);
+        return true;
+
+    }
+}