Answers for "comparable interface"

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;  
}  
}

comparable on a generic class java

public class DoubleKey<K extends Comparable<K>, J extends Comparable<J>>
        implements Comparable<DoubleKey<K, J>> {

    private K key1;
    private J key2;

    public DoubleKey(K key1, J key2) {
        this.key1 = key1;
        this.key2 = key2;
    }

    public K getFirstKey() {
        return this.key1;
    }

    public J getSecondKey() {
        return this.key2;
    }

    public int compareTo(DoubleKey<K, J> that) {

        int cmp = this.getFirstKey().compareTo(that.getFirstKey());
        if (cmp == 0)
            cmp = this.getSecondKey().compareTo(that.getSecondKey());
        return cmp;
    }
}

comparable interface java

public class BinarySearchTree< T extends Comparable<T>> {
    Node root;
    class Node {
        T data;
        Node left;
        Node right;

        public Node(T data) {
            this.data = data;
        }
    }

    public boolean isEmpty() {
        return root == null;
    }

    public void insert(T value) {
        if(isEmpty())
            root = new Node(value);
        else
            insert(root, value);
    }

    private void insert(Node node, T value) {

        if(value.compareTo(node.data) < 0) {
            if(node.left == null)
                node.left = new Node(value);
            else
                insert(node.left, value);
        }
        else {
            if(node.right == null)
                node.right = new Node(value);
            else
                insert(node.right, value);
        }
    }

}

comparable

+------------------------------------------------------------------------------------+
¦               Comparable                ¦                Comparator                ¦
¦-----------------------------------------+------------------------------------------¦
¦ java.lang.Comparable                    ¦ java.util.Comparator                     ¦
¦-----------------------------------------+------------------------------------------¦
¦ int objOne.compareTo(objTwo)            ¦ int compare(objOne, objTwo)              ¦
¦-----------------------------------------+------------------------------------------¦
¦ Negative, if objOne < objTwo            ¦ Same as Comparable                       ¦
¦ Zero,  if objOne == objTwo              ¦                                          ¦
¦ Positive,  if objOne > objTwo           ¦                                          ¦
¦-----------------------------------------+------------------------------------------¦
¦ You must modify the class whose         ¦ You build a class separate from to sort. ¦
¦ instances you want to sort.             ¦ the class whose instances you want       ¦
¦-----------------------------------------+------------------------------------------¦
¦ Only one sort sequence can be created   ¦ Many sort sequences can be created       ¦
¦-----------------------------------------+------------------------------------------¦
¦ Implemented frequently in the API by:   ¦ Meant to be implemented to sort          ¦
¦ String, Wrapper classes, Date, Calendar ¦ instances of third-party classes.        ¦
+------------------------------------------------------------------------------------+