小编use*_*224的帖子

嗨,我是java的新手,因为我知道set collection不会重复,当contains已经存在于collection中时,它的contains方法应该返回true.我试图在程序下运行,但我得到了意想不到的结果.

public class UserDefinedName {
    private final String first, last;

    public UserDefinedName(String first, String last) {
        this.first = first;
        this.last = last;
    }

    public boolean equals(Object o) {
        if (!(o instanceof UserDefinedName))
            return false;
        UserDefinedName n = (UserDefinedName) o;
        return n.first.equals(first) && n.last.equals(last);
    }

    public static void main(String[] args) {
        Set<UserDefinedName> s = new HashSet<UserDefinedName>();
        s.add(new UserDefinedName("Carballo", "Videl"));
        System.out.println(s.contains(new UserDefinedName("Carballo", "Videl")));
    }
}

我期待输出为true但程序打印为false.我做错了什么？