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 T getOldest() {
-        if (members.isEmpty()) {
+		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);
+		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 oldestMember;
+		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

@@ -1,6 +1,6 @@
 package _5._3;
 
-public class Person<T extends Older> implements Older<T> {
+public class Person implements Older<Person> {
 	private String name;
 	private int age;
 
@@ -9,15 +9,16 @@ public class Person<T extends Older> implements Older<T> {
 		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());
+	}
+}