java - Code runs fine in Eclipse but throws NumberFormatException in CodeChef -

the code working fine on eclipse ide on codechef, compiler showing error:

exception in thread "main" java.lang.numberformatexception: null     @ java.lang.integer.parseint(integer.java:542) @ java.lang.integer.parseint(integer.java:615) @ codechef.main(main.java:19) 

here's code:

import java.util.*; import java.lang.*; import java.io.*; class codechef {     public static void main(string[] args) throws ioexception     {         int x = 0, j = 0;         string s;         int counta = 0, countb = 0;         int countf[] = new int[5];         bufferedreader br = new bufferedreader(new inputstreamreader(system.in));         int = integer.parseint(br.readline());         while (j < i) {             s = br.readline();             (int k = 0; k < s.length(); k++) {                 if (s.charat(k) == 'a') {                     counta++;                 }                 else {                     countb++;                 }             }             if (counta < countb) {                 countf[j] = counta;             }             else {                 countf[j] = countb;             }             j++;             counta = countb = 0;         }          (int g = 0; g < i; g++) {             system.out.println(countf[g]);         }     } } 

i tried using scanner class in showing nosuchelementexception.

your problem here:

int = integer.parseint(br.readline()); 

you trying parse integer input not validating if input is can parsed integer

you need validate input , go forward when input correct is:

example

int = -1;     while (i == -1) {         try {         = integer.parseint(br.readline());         } catch (numberformatexception e) {         system.out.println("wrong input");         }     }