HackerRank Java- Lambda Expressions

Write the following methods that return a lambda expression performing a specified action:

PerformOperation isOdd(): The lambda expression must return true if a number is odd or false if it is even.
PerformOperation isPrime(): The lambda expression must return true if a number is prime or false if it is composite.
PerformOperation isPalindrome(): The lambda expression must return true if a number is a palindrome or false if it is not.

import java.io.*;
import java.util.*;
interface PerformOperation {
 boolean check(int a);
}
class MyMath {
 public static boolean checker(PerformOperation p, int num) {
  return p.check(num);
 }
public static PerformOperation isOdd() {
        return n -> (n & 1) == 1;
    }

    public static PerformOperation isPrime() {
        return n -> {
            if (n < 2) {
                return false;
            } else if (n == 2) {
                return true;
            } else if (n % 2 == 0) {
                return false;
            }
            int sqrt = (int) Math.sqrt(n);
            for (int i = 3; i <= sqrt; i += 2) {
                if (n % i == 0) {
                    return false;
                }
            }
            return true;
        };
    }

    public static PerformOperation isPalindrome() {
        return n -> {
            String original = Integer.toString(n);
            String reversed = new StringBuilder(Integer.toString(n)).reverse().toString();
            return original.equals(reversed);
        };
    }
}
   
public class Solution {

 public static void main(String[] args) throws IOException {
  MyMath ob = new MyMath();
  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  int T = Integer.parseInt(br.readLine());
  PerformOperation op;
  boolean ret = false;
  String ans = null;
  while (T--> 0) {
   String s = br.readLine().trim();
   StringTokenizer st = new StringTokenizer(s);
   int ch = Integer.parseInt(st.nextToken());
   int num = Integer.parseInt(st.nextToken());
   if (ch == 1) {
    op = ob.isOdd();
    ret = ob.checker(op, num);
    ans = (ret) ? "ODD" : "EVEN";
   } else if (ch == 2) {
    op = ob.isPrime();
    ret = ob.checker(op, num);
    ans = (ret) ? "PRIME" : "COMPOSITE";
   } else if (ch == 3) {
    op = ob.isPalindrome();
    ret = ob.checker(op, num);
    ans = (ret) ? "PALINDROME" : "NOT PALINDROME";

   }
   System.out.println(ans);
  }
 }
}