When I run my code in VS code it works, but at codeJudge I get a NullPointerException?
Does anyone know why and how to solve it?
package com.codegym.task.task07.task0727;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
/*
Changing functionality
*/
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
ArrayList<String> firstList = new ArrayList<String>();
while (true) {
String s = reader.readLine();
if (s.isEmpty())
break;
firstList.add(s);
}
ArrayList<String> list = new ArrayList<String>();
for (int i = 0; i < firstList.size(); i++) {
String s = firstList.get(i);
if (s.length() % 2 == 0) {
list.add(s + " " + s);
}
if (s.length() % 2 == 1) {
list.add(s + " " + s + " " + s);
}
}
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
}