I'll getting null pointer exception

package com.codegym.task.task07.task0726; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; /* Cat code won't compile */ public class Solution { public final static ArrayList<Cat> CATS = new ArrayList<>(); public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); while (true) { String name = reader.readLine(); int age = Integer.parseInt(reader.readLine()); int weight = Integer.parseInt(reader.readLine()); int tail = Integer.parseInt(reader.readLine()); // System.out.println(name+""+age+""+weight+""+tail); if (name.isEmpty()){ break; } Cat cat = new Cat(name, age, weight, tail); CATS.add(cat); } printList(); } public static void printList() { for (Cat cat : CATS) { System.out.println(cat); } } public static class Cat { private String name; private int age; private int weight; private int tailLength; Cat(String name, int age, int weight, int tailLength) { this.name = name; this.age = age; this.weight = weight; this.tailLength = tailLength; } @Override public String toString() { return "Cat's name: " + name + ", age: " + age + ", weight: " + weight + ", tail: " + tailLength; } } }