博客

1、map可以用来对集合元素做统一处理

List lsit3 = Stream.of(1,7,3).map(num -> num*=2).collect(Collectors.toList());
lsit3.forEach(num -> System.out.println(num));

2、对集合元素过滤

定义过滤条件将满足条件的元素保留

Stream<Integer> integerStream = Stream.of(1, 5, 2, 5, 1, 0).filter(res -> res % 2 == 0);
integerStream.forEach(num -> System.out.println(num));

3、对集合进行合并

List<Integer> list = new ArrayList<>();
list.add(1);
list.add(7);
list.add(3);
List<Integer> list2 = new ArrayList<>();
list2.add(8);
list2.add(1);
list2.add(7);

List<Integer> collect = Stream.of(list, list2).flatMap(lis -> lis.stream()).collect(Collectors.toList());
collect.forEach(x -> System.out.println(x));

4、对集合元素求和

System.out.println(Stream.of(2, 3, 5, 3, 9, 9, 7).reduce(0,(sum, x) -> sum + x));