- collect在流中生成列表,map,等常用的数据结构
- toList()
- toSet()
- toMap()
- 自定义
/** * toList */ public static void toListTest(){ List<PersonModel> data = Data.getData(); List<String> collect = data.stream() .map(PersonModel::getName) .collect(Collectors.toList()); } /** * toSet */ public static void toSetTest(){ List<PersonModel> data = Data.getData(); Set<String> collect = data.stream() .map(PersonModel::getName) .collect(Collectors.toSet()); } /** * toMap */ public static void toMapTest(){ List<PersonModel> data = Data.getData(); Map<String, Integer> collect = data.stream() .collect( Collectors.toMap(PersonModel::getName, PersonModel::getAge) ); data.stream() .collect(Collectors.toMap(per->per.getName(), value->{ return value+"1"; })); } /** * 指定类型 */ public static void toTreeSetTest(){ List<PersonModel> data = Data.getData(); TreeSet<PersonModel> collect = data.stream() .collect(Collectors.toCollection(TreeSet::new)); System.out.println(collect); } /** * 分组 */ public static void toGroupTest(){ List<PersonModel> data = Data.getData(); Map<Boolean, List<PersonModel>> collect = data.stream() .collect(Collectors.groupingBy(per -> "男".equals(per.getSex()))); System.out.println(collect); } /** * 分隔 */ public static void toJoiningTest(){ List<PersonModel> data = Data.getData(); String collect = data.stream() .map(personModel -> personModel.getName()) .collect(Collectors.joining(",", "{", "}")); System.out.println(collect); } /** * 自定义 */ public static void reduce(){ List<String> collect = Stream.of("1", "2", "3").collect( Collectors.reducing(new ArrayList<String>(), x -> Arrays.asList(x), (y, z) -> { y.addAll(z); return y; })); System.out.println(collect); }