Java stream根據對象某個字段過濾重復數據：distinctByKey

一、原生的distinct()不支持按照列表里的對象某個屬性去重

 

二、對某個字段過濾重復數據：使用HashMap

private static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
        Map<Object, Boolean> seen = new ConcurrentHashMap<>();
        return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
    }

list.stream().filter(distinctByKey(User::getId)).collect(Collectors.toList());

 

 

 

參考：

https://www.cnblogs.com/unknows/p/13534953.html