该代码似乎失败了，因为它想将它们进行比较FootballClub以匹配两者team1，team2并且除非team1等于，否则它不会为真team2。

如果任务是验证FootballClub实例列表是否包含具有给定名称的俱乐部，则应实现一个单独的简单方法：

static boolean clubListHasTeam(List<FootballClub> clubs, String team) {
    boolean found = false;

    for (FootballClub club : clubs) {
        if (club.getClubName().equals(team)) {
            found = true;
            break;
        }
    }
    return found;
}

使用Java Stream API有助于使此方法更简洁：

static boolean clubListHasTeam(List<FootballClub> clubs, String team) {
    return clubs.stream()
                .map(FootballClub::getClubName) // stream of the club names
                .anyMatch(team::equals);  // any club name matched the input name
}

用法：

String team1 = userInput.nextLine();
String team2 = userInput.nextLine();
boolean valid = true;

if (!clubListHasTeam(addStats, team1)) {
    System.out.println(team1 + " is invalid");
    valid = false;
}
if (!clubListHasTeam(addStats, team2)) {
    System.out.println(team2 + " is invalid");
    valid = false;
}