如何处理对象无法满足java 8流中的过滤器

Question

I am trying to process object which is failed to satisfy the filter condition in the stream.

List<Integer> list = Arrays.asList(1,23,43,12,4,5);
list.stream().filter( i -> i > 10).collect(Collections.toList);

This will return a list of Object greater than 10. but I also want to process the objects which are unable to satisfy the condition (>10).

Thank You.

Answer 1

Map<Boolean, List<Integer>> map = list.stream()
              .collect(Collectors.partitioningBy(i > 10));


map.get(false/true).... do whatever you want with those that failed or not

Answer 2

I would just run two sweeps with stream() to get two different lists:

List<Integer> list = Arrays.asList(1,23,43,12,4,5);

List<Integer> largerThanTen = list.stream().filter( i -> i > 10)
                                 .collect(Collectors.toList());
List<Integer> smallerOrEqualToTen = list.stream().filter( i -> i <= 10)
                                .collect(Collectors.toList());

I think this is more readable than trying to do it in a one-liner, resulting in a less-idiomatic data structure.

Answer 3

List<Integer> list = Arrays.asList(1,23,43,12,4,5);
list.stream().filter( i -> i > 10).collect(Collections.toList);

change to

Map < Boolean, List < Integer > > map = Stream.of( 1, 23, 43, 12, 4, 5 ).collect( Collectors.groupingBy( e -> e > 10 ) );

then you can use :

map.get( false )// is list of has not condition
map.get(true) // is list of has condition