小编Nam*_*jug的帖子

在Spring MVC框架中的LocalDateTime(Java 8)格式化中遇到问题

我的VO就像代码一样

在mySQL w_date字段中是DATETIME并重新编码"2015-12-25 23:18:22"

public class HistoryBoard { 
    @JsonFormat(pattern="yyyy-MM-dd")
    @DateTimeFormat(iso = DateTimeFormat.ISO.TIME)
    private LocalDateTime w_date;


    public LocalDateTime getW_date() {
        return w_date;
    }

    public HistoryBoard setW_date(String w_date) {
        DateTimeFormatter sdf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.S");
        this.w_date = LocalDateTime.parse(w_date, sdf);
        return this;
    }
}

添加maven依赖

<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-jsr310</artifactId>
    <version>2.5.3</version>
</dependency>

并添加@JsonFormat(pattern="yyyy-MM-dd")字段值w_date

但仍然json得到像对象

"w_date":{"dayOfMonth":25,"dayOfWeek":"FRIDAY","month":"DECEMBER","year":2015,"dayOfYear":359,"monthValue":12,"hour":23,"minute":18,"second":22,"nano":0,"chronology":{"id":"ISO","calendarType":"iso8601"}

json页面控制器代码

@RequestMapping(value = "/listJson.do")
public @ResponseBody Object listJson(Map<String, Object> commandMap, ModelMap model) throws Exception {
    List<HistoryBoard> list = boardService.selectBoardList(commandMap);
    return …

我有一张地图:

private Map<String, AtomicInteger> keywordMap = new HashMap<String, AtomicInteger>();

我正在尝试使用以下代码对Java 8中的Mapby value(AtomicInteger)进行排序:

keywordMap
        .entrySet()
        .parallelStream()
        .sorted().forEachOrdered(e -> System.out.print(e.getKey()));

但是,我收到以下错误:

java.lang.ClassCastException: java.util.HashMap$Node cannot be cast to java.lang.Comparable

此行中发生错误: .forEachOrdered(e -> System.out.print(e.getKey()));

我的代码出了什么问题？