Не понимаю чего не учёл
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;
}
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof Solution)) return false;
if (o.getClass() != this.getClass()) {
return false;
}
Solution n = (Solution) o;
return n.first != null
&& n.last != null
&& n.first.equals(first)
&& n.last.equals(last);
}
public int hashCode() {
int part1 = first == null ? 1 : first.hashCode();
int part2 = last == null ? 1 : last.hashCode();
return 31 * part1 + part2;
}
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")));
}
}