getClass() != n.getClass() разве тут я это не проверяю?
package com.javarush.task.task21.task2104;
import java.util.HashSet;
import java.util.Objects;
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 n) {
// System.out.println("12312");
if (this==n) return true;
if (n==null || this.getClass() != n.getClass()) return false;
Solution x = (Solution) n ;
return first==x.first && last ==x.last;
}
public int 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.hashCode());
// System.out.println(new Solution("Donald", "Duck").hashCode() );
System.out.println(s.contains(new Solution("Donald", "Duck")));
// System.out.println(s.contains(s));
}
}