导入HashMap时出错

Question

您好，我正在使用 eclips indigo 开发我的项目，但我的包中出现错误 - 像这样

此行有多个标记 - java.util.Map$Entry 类型无法解析。它间接引用自 所需的 .class 文件 - java.util.Map$Entry 类型无法解析。它间接引用自 所需的 .class 文件

有谁知道为什么我在我的 java 类中导入 Hashmap,util.map,common.collect.map 时会出错

package info.sample.project;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
import org.json.JSONException;
import org.json.JSONObject;
import com.google.common.collect.Maps;

 @ServerEndpoint("/chat")
  public class SocketServer {

   // set to store all the live sessions
   private static final Set<Session> sessions = Collections
        .synchronizedSet(new HashSet<Session>());

  // Mapping between session and person name
private static final HashMap<String, String> nameSessionPair = new    HashMap<String, String>();

private JSONUtils jsonUtils = new JSONUtils();

// Getting query params
public static Map<String, String> getQueryMap(String query) {
    Map<String, String> map = Maps.newHashMap();
    if (query != null) {
        String[] params = query.split("&");
        for (String param : params) {
            String[] nameval = param.split("=");
            map.put(nameval[0], nameval[1]);
        }
    }
    return map;
}

/**
 * Called when a socket connection opened
 * */
@OnOpen
public void onOpen(Session session) {

    System.out.println(session.getId() + " has opened a connection");

    Map<String, String> queryParams = getQueryMap(session.getQueryString());

    String name = "";

    if (queryParams.containsKey("name")) {

        // Getting client name via query param
        name = queryParams.get("name");
        try {
            name = URLDecoder.decode(name, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        // Mapping client name and session id
        nameSessionPair.put(session.getId(), name);
    }

    // Adding session to session list
    sessions.add(session);

    try {
        // Sending session id to the client that just connected
        session.getBasicRemote().sendText(
                jsonUtils.getClientDetailsJson(session.getId(),
                        "Your session details"));
    } catch (IOException e) {
        e.printStackTrace();
    }

    // Notifying all the clients about new person joined
    sendMessageToAll(session.getId(), name, " joined conversation!", true,
            false);

}

/**
 * method called when new message received from any client
 * 
 * @param message
 *            JSON message from client
 * */
@OnMessage
public void onMessage(String message, Session session) {

    System.out.println("Message from " + session.getId() + ": " + message);

    String msg = null;

    // Parsing the json and getting message
    try {
        JSONObject jObj = new JSONObject(message);
        msg = jObj.getString("message");
    } catch (JSONException e) {
        e.printStackTrace();
    }

    // Sending the message to all clients
    sendMessageToAll(session.getId(), nameSessionPair.get(session.getId()),
            msg, false, false);
}

/**
 * Method called when a connection is closed
 * */
@OnClose
public void onClose(Session session) {

    System.out.println("Session " + session.getId() + " has ended");

    // Getting the client name that exited
    String name = nameSessionPair.get(session.getId());

    // removing the session from sessions list
    sessions.remove(session);

    // Notifying all the clients about person exit
    sendMessageToAll(session.getId(), name, " left conversation!", false,
            true);

}

/**
 * Method to send message to all clients
 * 
 * @param sessionId
 * @param message
 *            message to be sent to clients
 * @param isNewClient
 *            flag to identify that message is about new person joined
 * @param isExit
 *            flag to identify that a person left the conversation
 * */
private void sendMessageToAll(String sessionId, String name,
        String message, boolean isNewClient, boolean isExit) {

    // Looping through all the sessions and sending the message individually
    for (Session s : sessions) {
        String json = null;

        // Checking if the message is about new client joined
        if (isNewClient) {
            json = jsonUtils.getNewClientJson(sessionId, name, message,
                    sessions.size());

        } else if (isExit) {
            // Checking if the person left the conversation
            json = jsonUtils.getClientExitJson(sessionId, name, message,
                    sessions.size());
        } else {
            // Normal chat conversation message
            json = jsonUtils
                    .getSendAllMessageJson(sessionId, name, message);
        }

        try {
            System.out.println("Sending Message To: " + sessionId + ", "
                    + json);

            s.getBasicRemote().sendText(json);
        } catch (IOException e) {
            System.out.println("error in sending. " + s.getId() + ", "
                    + e.getMessage());
            e.printStackTrace();
        }
    }
}
   }

Answer 1

也尝试导入java.util.Map.Entry。