В чем проблема у меня?
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;
}
@Override
public boolean equals(Object o) {
if (o == null) {
return false;
}
if (!(o instanceof Solution)) {
return false;
}
if (this == o) return true;
Solution sol = (Solution) o;
if (first == null && sol.first == null && last == null && sol.last == null) return true;
if ((first == null && sol.first != null) ||
(first != null && sol.first == null) ||
(!first.equals(sol.first))) return false;
if ((last == null && sol.last != null) || (last != null && sol.last == null) || (!last.equals(sol.last))) return false;
return true;
}
@Override
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.contains(new Solution("Donald", "Duck")));
}
}