Почему не закрывается цикл while при вводе пустой строки?

public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); ArrayList<String> strings = new ArrayList<String>(); while (true) { String string = reader.readLine(); if (string == null || string.isEmpty()) { break; } strings.add(string); } ArrayList<String> resultStrings = new ArrayList<String>(); for (int i = 0; i < strings.size(); i++) { int a = strings.get(i).length(); if(a % 2 == 0){ strings.add(i,strings.get(i) + " " + strings.get(i)); } if(a % 2 != 0){ strings.add(i,strings.get(i) + " " + strings.get(i) + " " + strings.get(i)) ; } } for (int i = 0; i < resultStrings.size(); i++) { System.out.println(resultStrings.get(i)); } } }