Java 流迭代列表<；对象>；上的NoSuchElementException

发布于03月09日

嗨! try 使用此流，但我打开了NoSuchElementException

var scores = findAllByBarcode
                .stream()
                .iterator()
                .next()
                        .getMpProductFeedbacks()
                                .stream()
                                        .filter(mpProductFeedback -> mpProductFeedback.getId()==mpProductFeedbackId)
                                               .iterator()
                .next()
                .getMpPersonScores()
                .stream()
                .map(mpPersonScore -> {
                            var score = new ScoreType();
                            score.setUserScore(mpPersonScore.getMpPersonScore());
                            score.setUser(mpPersonScore.getMpPersonLogin());
                            score.setUserComment(mpPersonScore.getMpPersonComment());
                            return score;
                })
    .toList();

部件后出现异常

filter(mpProductFeedback -> mpProductFeedback.getId()==mpProductFeedbackId)
                                           .iterator()
            .next()

try 使用orElse，但它只能与.equals一起使用我已经有了==在两只长龙之间.

推荐答案

假设我们正在处理嵌套集合

List<ScoreType> scores = findAllByBarcode
    .stream()
    .map( b -> b.getMpProductFeedbacks() )
    .flatMap( Collection::stream )
    .filter( feedback -> feedback.getId() == mpProductFeedbackId )
    .map( feedback -> feedBack.getMpPersonScores() )
    .flatMap( Collection::stream )
    .map( personScore -> {
        ScoreType score = new ScoreType();
        score.setUserScore( personScore.getMpPersonScore() );
        score.setUser( personScore.getMpPersonLogin() );         
        score.setUserComment( personScore.getMpPersonComment() );
        return score;
    })
   .toList();