Скажите, что я тут не так проверяю, или что-то забыл?
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 == this) return true;
if (n == null) return false;
if (!(n instanceof Solution)) return false;
Solution obj = (Solution) n;
if (this.first == null || this.last == null) return false;
if (this.first.equals(obj.first) && this.last.equals(obj.last)) {
return true;
}else return false;
}
public int hashCode() {
return 31 * first.hashCode() + last.hashCode();
}
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")));
}
}