Не могу понять в чем дело. Сначала не проходило 3-е условие. Потом я добавил 21 строку и перестало проходить 4е. Помогите разобраться! Заранее благодарен.
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 (this == o) return true;
//if (o instanceof Solution) return true;
if (o == null || getClass() != o.getClass()) return false;
Solution solution = (Solution) o;
return (((first==null&&solution.first==null)||(first!=null&&solution.first!=null)&&(first.equals(solution.first)) &&
(last==null&&solution.last==null)||(last!=null&&solution.last!=null)&&(last.equals(solution.last))));
}
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + (first == null ? 0 : first.hashCode());
result = prime * result + (last == null ? 0 : last.hashCode());
return result;
}
public static void main(String[] args) {
Set<Solution> s = new HashSet<Solution>();
s.add(new Solution("Donald", "Duck"));
s.add(new Solution(null, "Duck"));
s.add(new Solution("Donald", null));
s.add(new Solution(null, null));
System.out.println(s.contains(new Solution("Donald", "Duck")));
System.out.println(s.contains(new Solution(null, "Duck")));
System.out.println(s.contains(new Solution("Donald", null)));
System.out.println(s.contains(new Solution(null, null)));
//test
//for (Solution x : s){
//System.out.println(x.equals(new Solution("Donald", "Duck")));
// }
}
}