implementing comparable java code example

Example 1: comparable interfacee

class Student implements Comparable<Student>{  
int rollno;  
String name;  
int age;  
Student(int rollno,String name,int age){  
this.rollno=rollno;  
this.name=name;  
this.age=age;  
}  
  
public int compareTo(Student st){  
if(age==st.age)  
return 0;  
else if(age>st.age)  
return 1;  
else  
return -1;  
}  
}

Example 2: T implements comparable

public static class Node<T extends Comparable<T>> { //HERE

    private T value;

    public Node(T val) {
        this.value = val;
    }

    public void insert(T val) {
        if (value.compareTo(val) > 0) {
            new Node<T>(val);
        }
    }
}