Improvements for 5.3

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

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

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

@@ -1,7 +1,5 @@
 package _5._3;
 
 public interface Older<T> {
-    public boolean isOlder(T other);
-
-    public int getAge();
+	boolean isOlder(T other);
 }

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

@@ -1,23 +1,24 @@
 package _5._3;
 
-public class Person<T extends Older> implements Older<T> {
-    private String name;
-    private int age;
+public class Person implements Older<Person> {
+	private String name;
+	private int age;
 
-    public Person(String name, int age) {
-        this.name = name;
-        this.age = age;
-    }
+	public Person(String name, int age) {
+		this.name = name;
+		this.age = age;
+	}
 
-    public int getAge() {
-        return age;
-    }
+	@Override
+	public boolean isOlder(Person other) {
+		return this.getAge() > other.getAge();
+	}
 
-    public String getName() {
-        return name;
-    }
+	public int getAge() {
+		return this.age;
+	}
 
-    public boolean isOlder(T other) {
-        return this.age > other.getAge();
-    }
+	public String getName() {
+		return this.name;
+	}
 }

src/main/java/provided/_5/_3/TestGroup.java

@@ -0,0 +1,14 @@
+package provided._5._3;
+
+import _5._3.Group;
+import _5._3.Person;
+
+public class TestGroup {
+	public static void main(String[] args) {
+		Group<Person> group = new Group<>();
+		group.add(new Person("Alice", 25));
+		group.add(new Person("Bob", 23));
+		group.add(new Person("Carl", 26));
+		System.out.println(group.getOldest().getName());
+	}
+}