Задача 2104. Не принимает по 4 пункту.

package com.javarush.task.task21.task2104; import java.util.HashSet; import java.util.Set; /* Equals and HashCode */ public class Solution { private final String first, last; public Solution(String first, String last) { this.first = first; this.last = last; } @Override public boolean equals(Object n) { if (n == null) return false; if (this == n) return true; //if (getClass() != n.getClass()) // return false; if (!(n instanceof Solution)) return false; Solution other = (Solution) n; if (first != null ? !first .equals(other.first) : first != null) return false; if (last != null ? !last.equals(other.last) : last != null) return false; return true; } @Override public int hashCode() { final int prime = 31; int result = 1; result = first != null ? first.hashCode() : 0; result = prime * result + (last != null ? last.hashCode() : 0); return result; } public static void main(String[] args) { Set<Solution> s = new HashSet<>(); s.add(new Solution("Donald", "Duck")); System.out.println(s.contains(new Solution("Donald", "Duck"))); //s.add(new Solution("dfdf", "dfdf1")); //System.out.println(s.contains(new Solution("dfdf", "dfdf1"))); } }