从列表中删除日期比较

Question

我必须删除之前param.getFromDateTime和之后的所有对象params.getToDateTime。我是这样做的：

for (ListIterator<Doc> iterator = doc.listIterator(); iterator.hasNext(); ) {

    while(iterator.hasNext()){

            if(param.getFromDateTime() != null

              && doc.get(iterator.nextIndex()).getDate().before(params.getFromTime())) {

                iterator.remove();

            }

            if(params.getToDateTime() != null

              && doc.get(iterator.nextIndex()).getDate().after(params.getToDateTime())) {

                iterator.remove();

           }

    }

}

我可以做得更好更清晰吗？

Answer 1

您不需要两个循环，也不需要ListIterator。请注意，这两个条件可能为真，但在任何情况下您都只想删除一个元素，因为调用两次remove()会引发异常。您还可以直接date从迭代Doc对象中提取 ，使其更加清晰：for (Iterator<Doc> iterator = doc.iterator(); iterator.hasNext(); ) {&nbsp; &nbsp; &nbsp; Date date = iterator.next().getDate();&nbsp; &nbsp; &nbsp; if( (param.getFromDateTime() != null && date.before(params.getFromTime()))&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; || (params.getToDateTime() != null && date.after(params.getToDateTime()))) {&nbsp; &nbsp; &nbsp; &nbsp; iterator.remove();&nbsp; &nbsp; &nbsp; }}

Answer 2

List.removeIf如果您使用的是 Java 8，您可能需要使用：List<Doc> docs = generateSomeValues(); // this ist just an imaginary filling of the list// check if the params are not null and remove dates that are not in the given intervaldocs.removeIf(doc ->&nbsp; &nbsp; (params.getFromTime() != null && doc.getDate().before(params.getFromTime()))&nbsp; &nbsp; || (params.getToDateTime() != null && doc.getDate().after(params.getToDateTime())));

Answer 3

带有流 api 的 java-8 近似：List<Doc> docs = ...;Stream<Doc> stream = docs.stream();LocalDateTime fromDateTime = param.getFromDateTime();LocalDateTime toDateTime = param.getToDateTime();if (fromDateTime != null){&nbsp; &nbsp; stream = stream.filter(d -> !d.getDate().before(fromDateTime);}if (toDateTime != null){&nbsp; &nbsp; stream = stream.filter(d -> !d.getDate().after(toDateTime);}docs = stream.collect(Collectors.toList());