java stream 总结

/**
 * 测试
 *
 * @param args 参数实体
 */
public static void main(String args[]) {
    List<SeatVo> list = new ArrayList<>();
    for (int i = 1; i <= 20; i++) {
        list.add(new SeatVo((long) i, "坐席" + i, i % 2 == 0 ? "空闲" : "忙碌"));
    }
    //排序-倒叙
    System.out.println("排序-倒叙-------------------------------------------------------------------------------------------");
    List<SeatVo> collect = list.stream().sorted(Comparator.comparing(SeatVo::getSeatId).reversed()).collect(Collectors.toList());
    collect.stream().forEach(vo -> {
        System.out.println("collect=" + vo.toString());
    });
    //filter-过滤器
    System.out.println("filter-过滤器-------------------------------------------------------------------------------------------");
    List<SeatVo> voList = list.stream().filter(vo -> StringUtil.equals("忙碌", vo.getSeatState())).collect(Collectors.toList());
    voList.stream().forEach(vo -> {
        System.out.println("voList=" + vo.toString());
    });
    //filter-提取元素
    System.out.println("filter-提取元素-------------------------------------------------------------------------------------------");
    List<String> stringList = list.stream().map(SeatVo::getSeatState).collect(Collectors.toList());
    stringList.stream().forEach(vo -> {
        System.out.println("stringList=" + vo);
    });
    //filter-去重
    System.out.println("filter-去重-------------------------------------------------------------------------------------------");
    Stream<String> distinct = stringList.stream().distinct();
    distinct.forEach(vo -> {
        System.out.println("distinct=" + vo);
    });
    //filter-分组
    System.out.println("filter-分组-------------------------------------------------------------------------------------------");
    Map<String, List<SeatVo>> listMap = list.stream().collect(Collectors.groupingBy(SeatVo::getSeatState));
    listMap.keySet().forEach(vo->{
        System.out.println("listMap key = "+vo);
        List<SeatVo> vvList = listMap.get(vo);
        vvList.forEach(vv->{
            System.out.println("vvList = "+vv);
        });
    });
}