Instructions

https://www.codewars.com/kata/5539fecef69c483c5a000015/train/java

Solution:

public class BackWardsPrime {			public static String backwardsPrime(long start, long end) {		StringBuilder sb = new StringBuilder();				for(long i = start; i <= end; i++){			if(i % 2 == 0){				continue;			}			long backwardRead = Long.valueOf(new StringBuilder(String.valueOf(i)).reverse().toString());			if(isPrime(i) && !isPalindrome(i) && isPrime(backwardRead)){				sb.append(String.valueOf(i)).append(" ");			}		}		return sb.toString().trim();	}		private static boolean isPalindrome(long a){		String str = String.valueOf(a);		int len = str.length();		for(int i = 0; i < len / 2; i++){			if(str.charAt(i) != str.charAt(len - 1 - i)){				return false;			}		}		return true;	}		private static boolean isPrime(long a){		if(a < 2){ // A prime number is no less than 2			return false;		}else{			for(int i = 2; i <= Math.sqrt(a); i++){				if(a % i == 0){					return false;				}			}		}				return true;	}}

Sample Tests:

https://www.codewars.com/kata/5539fecef69c483c5a000015/train/java