java.util.TreeMap$Entry.entrySet() 适用于参数类型：() 值：[]

Question

我有ChatDayWrappers，其中包含一天内双方数据库中的所有消息。

如何从对象chatWrapper.getChatDayWrappers()[0]; 中获取包含 47 个项目的 chatRowWrappers？

代码

Object object = chatWrapper.getChatDayWrappers()[0];            
getLogger().info("chatWrapper:  " + object.getClass().getName());

输出

java.util.TreeMap$Entry

再试一次：

我已经厌倦了以下内容：

Object object[] = chatWrapper.getChatDayWrappers()[0].entrySet().toArray();             
getLogger().info("chatWrapper:  " + object.getClass().getName());

但我收到了这个错误：

方法没有签名：java.util.TreeMap$Entry.entrySet() 适用于参数类型：() 值：[] 可能的解决方案：every(): groovy.lang.MissingMethodException: No signature of method: java.util.TreeMap$Entry.entrySet() is applicable for argument types: () values: []

CockpitChatWrapper

public class CockpitChatWrapper
        implements Serializable {

    private static final long serialVersionUID = 1L;

    public static final String STYLE_CHAT_UNKNOWN = "tpChatUnknown";
    public static final String STYLE_CHAT_FROM = "tpChatFrom";
    public static final String STYLE_CHAT_TO = "tpChatTo";

    /** Used to format the dates in the report. */
    private static final ThreadLocal<SimpleDateFormat> DATE_FORMAT = new ThreadLocal<SimpleDateFormat>() {

        @Override
        protected SimpleDateFormat initialValue() {
            return new SimpleDateFormat("yyyy-MM-dd");
        }
    };

    private final Map<String, ChatDisplayDayWrapper> chatDayWrappers;

    private final Long currentUserId;
    private final Long currentFlexiObjectId;


    /**
     * Constructor.
     * 
     * @param currentUserId The user Id.
     * @param currentFlexiObjectId The flexiObejct Id.
     */
    public CockpitChatWrapper(final Long currentUserId, final Long currentFlexiObjectId) {
        this.chatDayWrappers = new TreeMap<String, ChatDisplayDayWrapper>(new Comparator<String>() {

            public int compare(final String o1, final String o2) {
                return (o1.compareTo(o2) * -1);
            }

        });
        this.currentUserId = currentUserId;
        this.currentFlexiObjectId = currentFlexiObjectId;
    }


    /**
     * 
     * Add a chat entry.
     * 
     * @param chat The chat entry.
     */
    public void addChatEntry(final Chat chat) {

        String key = CockpitChatWrapper.DATE_FORMAT.get().format(chat.getLastWrite());
        ChatDisplayDayWrapper entry = null;
        if (this.chatDayWrappers.get(key) != null) {
            entry = this.chatDayWrappers.get(key);
        } else {
            entry = new ChatDisplayDayWrapper(chat.getLastWrite());
            this.chatDayWrappers.put(key, entry);
        }

        entry.addChat(chat, this.currentUserId, this.currentFlexiObjectId);
    }


    /**
     * Returns the chatDayWrappers.
     * 
     * @return Returns the chatDayWrappers.
     */
    public Object[] getChatDayWrappers() {
        return this.chatDayWrappers.entrySet().toArray();
    }


    public boolean getHasChatDayWrappers() {
        return this.chatDayWrappers != null && this.chatDayWrappers.size() > 0;
    }

    /**
     * 
     * Hold the chat entries for an day.
     * 
     */
    public static class ChatDisplayDayWrapper
            implements Serializable {

        private static final long serialVersionUID = 1L;

        private final Date day;
        private final List<ChatDisplayRowWrapper> chatRowWrappers;


        /**
         * 
         * Constructor.
         * 
         * @param day The day to set.
         */
        public ChatDisplayDayWrapper(final Date day) {
            this.day = day;
            this.chatRowWrappers = new ArrayList<ChatDisplayRowWrapper>();
        }


        private void addChat(final Chat chat, final Long currentUserId, final Long currentFlexiObjectId) {

            String styleClass = CockpitChatWrapper.STYLE_CHAT_UNKNOWN;

            if (currentUserId != null && chat.getFromUser() != null
                    && currentUserId.longValue() == chat.getFromUser().getId().longValue()) {
                styleClass = CockpitChatWrapper.STYLE_CHAT_FROM;
            } else if (currentFlexiObjectId != null && chat.getFromFlexiObject() != null
                    && currentFlexiObjectId.longValue() == chat.getFromFlexiObject().getId().longValue()) {
                styleClass = CockpitChatWrapper.STYLE_CHAT_TO;
            }
            this.chatRowWrappers.add(new ChatDisplayRowWrapper(chat, styleClass));
        }


        /**
         * Returns the day.
         * 
         * @return Returns the day.
         */
        public Date getDay() {
            return this.day;
        }


        /**
         * Returns the chatRowWrappers.
         * 
         * @return Returns the chatRowWrappers.
         */
        public List<ChatDisplayRowWrapper> getChatRowWrappers() {
            return this.chatRowWrappers;
        }

    }

}

截图

Answer 1

你的函数Object[] getChatDayWrappers：

this.chatDayWrappers.entrySet().toArray()

返回Map$Entry 的数组。例如：

groovy:000> [1:1].entrySet().toArray().first().getClass()
===> class java.util.LinkedHashMap$Entry

Entry不是地图，它只是一个条目。一个条目包含key 和value（但不包含entrySet()；这是您的代码失败的地方）。例如

groovy:000> [1:1].entrySet().toArray().first().key
===> 1
groovy:000> [1:1].entrySet().toArray().first().value
===> 1
groovy:000> [1:1].entrySet().toArray().first().entrySet()
ERROR groovy.lang.MissingMethodException:
No signature of method: java.util.LinkedHashMap$Entry.entrySet() is applicable for argument types: () values: []
Possible solutions: every()

因此，要获得显示包装器，您需要在 Groovy 中调用 value，或者因为您的代码看起来更像 Java，无论如何 .getValue() 以获取 ChatDisplayDayWrapper。

Answer 2

这里的问题是：

public Object[] getChatDayWrappers() {
        return this.chatDayWrappers.entrySet().toArray();
    } 

返回一个对象数组，您不能直接访问地图内的 ChatDisplayDayWrapper 对象。相反，您可以将 getter 修改为：

public List<ChatDisplayRowWrapper> getChatDayWrappers() {
    return m.entrySet().stream().map(entry -> entry.getValue()).collect(Collectors.toList());        }
}