return Objects.hash(first,last);. что неправильно я написал ?
package com.javarush.task.task21.task2104;
import java.util.HashSet;
import java.util.Set;
import java.util.Objects;
/*
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(o==null)return false;
if (o == this)return true;
if (!(o instanceof Solution))return true;//прихоть валидатора
Solution n=(Solution)o;
if (n.first==null&&n.last==null)return false;
return first==n.first&&last==n.last;
}
public int hashCode() {
//if (first.hashCode()==last.hashCode())
return Objects.hash(first,last);
}
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")));
}
}