Why does my code result in a compile error? : <p>The code in question is as follows:</p>

<pre><code>importjava.util.ArrayList;
importjava.util.Collections;
importjava.util.List;

public class Test{
    public static void main(String[] args) {
        List&lt;Human&gt; humans= newArrayList&lt;Human&gt;();
        humans.add(newHuman(13));
        humans.add(newHuman(33));
        humans.add(newHuman(21));
        humans.add(newHuman(21));
        Collections.sort(humans); 
        System.out.print(humans.get(0).age);
        System.out.print(humans.size()); 
    }
}
class Human implements Comparable&lt;Human&gt; {
    int age;
    public Human(int age) {
        this.age = age;
    }
    public int compareTo(Human h) {
        return h.age.compareTo(this.age);
    }
}
</code></pre>

<p>I was wondering why this code causes a compilation error? I'm not sure where I'm going wrong. </p>

<p>Some extra details: </p>
