Initial commit for 5.3

src/main/java/_5/_3/Group.java

@@ -0,0 +1,26 @@
+package _5._3;
+
+import java.util.LinkedList;
+
+public class Group<T extends Older> {
+    private LinkedList<T> members = new LinkedList<>();
+
+    public void add(T member) {
+        this.members.add(member);
+    }
+
+    public T getOldest() {
+        if (members.isEmpty()) {
+            return null;
+        }
+
+        T oldestMember = members.get(0);
+
+        for (int i=1; i<members.size(); i++) {
+            if (members.get(i).isOlder(oldestMember)) {
+                oldestMember = members.get(i);
+            }
+        }
+        return oldestMember;
+    }
+}

src/main/java/_5/_3/Older.java

@@ -0,0 +1,7 @@
+package _5._3;
+
+public interface Older<T> {
+    public boolean isOlder(T other);
+
+    public int getAge();
+}

src/main/java/_5/_3/Person.java

@@ -0,0 +1,23 @@
+package _5._3;
+
+public class Person<T extends Older> implements Older<T> {
+    private String name;
+    private int age;
+
+    public Person(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public boolean isOlder(T other) {
+        return this.age > other.getAge();
+    }
+}