Android 尝试调用虚拟方法'；void com.quickblox.chat.QBGroupChat.leave（）'；关于空对象引用

我有QBDialogType.GROUP类型的QBDialog。现在我想离开QB对话框。我正在使用下面的代码，但它不起作用，并且出现异常“尝试在空对象引用上调用虚拟方法'void com.quickblox.chat.QBGroupChat.leave（）”

QBRestChatService.getChatDialogById（dialogId）.performAsync(
新的QBEntityCallback（）{
@凌驾
成功时公共无效（QBChatDialog对话框，捆绑参数）{
试一试{
dialog.leave（）；
dialog=null；
}catch（XMPPException | smakexception.NotConnectedException e）{
e、 printStackTrace（）；
Log.e（标记“onSuccess:XMPPException=“+e.getMessage（）”）；
}捕获（例外e）{
e、 printStackTrace（）；
Log.e（标记“onSuccess:Groyup=“+e.getMessage（））；
}
}
@凌驾
公共无效报告人（QBResponseException-responseException）{
if（pd！=null&&pd.isShowing（））
pd.解散（）；
Log.e（标记“onError:Group Leaving Failed=“+responseException.getMessage（））；
}
});
QBASDK：*********************************************************
***响应***152689aa-b008-4ac1-9b7e-4DD3F124C80***
现状：200
标题
X-Runtime=0.150446
缓存控制=max age=0，私有，必须重新验证
X机架缓存=未命中
QuickBlox REST API版本=0.1.1
X-Android-Selected-Protocol=http/1.1
X-UA-Compatible=IE=Edge，chrome=1
QB代币到期日期=2017-01-07 07:57:15 UTC
状态=200正常
X-Request-Id=9c2eace158b29a9e4b782cefd64d9304
X-Android-Response-Source=网络200
连接=关闭
X-Android-Sent-Millis=1483768746154
内容类型=应用程序/json；字符集=utf-8
日期=2017年1月7日星期六05:59:00 GMT
服务器=openresty/1.9.15.1
ETag=“a1cfba7d8894969ce612ffa36ea52e83”
内容长度=423
严格的交通安全=最大年龄=15768000；
X-Android-Received-Millis=1483768746657
访问控制允许源=*
身体
“{”total_entries“：1，“skip“：0，“limit“：100，“items”：[{”\uID:“5870838ea28f9a9c39000020”，“created_at:“2017-01-07T05:58:38Z”，“last_message”：null，“last_message_date_sent”：null，“last__message_user_id:”null，“name:“Drinks”，“ids:[2225818022400060]，“photo:“photo:”鸡尾酒”，“type:2”，“Update_at:“2017-01-01-07T05:58:38Z”，“user_id:”用户id:“Jixmu房间”：”"51660_5870838ea28f9a9c39000020@muc.chat.quickblox.com“，“未读邮件数”：0}]}”
01-07 11:29:06.686 26084-26084/com.om.sigmatech.dating D/QBASDK:无法分析聊天对话框中的LastMessageDateSent字段
01-07 11:29:06.686 26084-26084/com.om.sigmatech.dating D/QBASDK:无法解析聊天对话框中的lastMessageUserId字段
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:java.lang.NullPointerException:尝试对空对象引用调用虚拟方法“void com.quickblox.chat.QBGroupChat.leave（）”
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:在com.quickblox.chat.model.QBChatDialog.leave（源文件：768）
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:at com.om.sigmatech.dating.MatchNotificationActivity$5.onSuccess（MatchNotificationActivity.java:313）
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:at com.om.sigmatech.dating.MatchNotificationActivity$5.onSuccess（MatchNotificationActivity.java:306）
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:at com.quickblox.auth.session.Query.notifySuccess（源文件：447）
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:at com.quickblox.auth.session.Query$VersionEntityCallback.completedWithResponse（源文件：483）
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:at com.quickblox.auth.session.Query.completedWithResponse（源文件：307）
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.e
QBRestChatService.getChatDialogById(dialogId).performAsync(
                    new QBEntityCallback<QBChatDialog>() {
                        @Override
                        public void onSuccess(QBChatDialog dialog, Bundle params) {

                          try {
                                dialog.leave();
                                dialog = null;

                            } catch (XMPPException | SmackException.NotConnectedException e) {
                                e.printStackTrace();
                                Log.e(TAG, "onSuccess: XMPPException=" + e.getMessage());
                            } catch (Exception e) {
                                e.printStackTrace();
                                Log.e(TAG, "onSuccess: Groyup=" + e.getMessage());
                            }
                        }

                        @Override
                        public void onError(QBResponseException responseException) {
                            if (pd != null && pd.isShowing())
                                pd.dismiss();
                            Log.e(TAG, "onError: Group Leaving Failed=" + responseException.getMessage());
                        }
                    });




QBASDK: *********************************************************
                                                                 *** RESPONSE *** 152689aa-b008-4ac1-9b7e-4ddd3f124c80 ***
                                                                 STATUS : 200 
                                                                 HEADERS
                                                                     X-Runtime=0.150446
                                                                     Cache-Control=max-age=0, private, must-revalidate
                                                                     X-Rack-Cache=miss
                                                                     QuickBlox-REST-API-Version=0.1.1
                                                                     X-Android-Selected-Protocol=http/1.1
                                                                     X-UA-Compatible=IE=Edge,chrome=1
                                                                     QB-Token-ExpirationDate=2017-01-07 07:57:15 UTC
                                                                     Status=200 OK
                                                                     X-Request-Id=9c2eace158b29a9e4b782cefd64d9304
                                                                     X-Android-Response-Source=NETWORK 200
                                                                     Connection=Close
                                                                     X-Android-Sent-Millis=1483768746154
                                                                     Content-Type=application/json; charset=utf-8
                                                                     Date=Sat, 07 Jan 2017 05:59:00 GMT
                                                                     Server=openresty/1.9.15.1
                                                                     ETag="a1cfba7d8894969ce612ffa36ea52e83"
                                                                     Content-Length=423
                                                                     Strict-Transport-Security=max-age=15768000;
                                                                     X-Android-Received-Millis=1483768746657
                                                                     Access-Control-Allow-Origin=*
                                                                 BODY
                                                                     '{"total_entries":1,"skip":0,"limit":100,"items":[{"_id":"5870838ea28f9a9c39000020","created_at":"2017-01-07T05:58:38Z","last_message":null,"last_message_date_sent":null,"last_message_user_id":null,"name":"Drinks","occupants_ids":[22258180,22400060],"photo":"cocktail","type":2,"updated_at":"2017-01-07T05:58:38Z","user_id":22400060,"xmpp_room_jid":"51660_5870838ea28f9a9c39000020@muc.chat.quickblox.com","unread_messages_count":0}]}'
01-07 11:29:06.686 26084-26084/com.om.sigmatech.dating D/QBASDK: Can't parse LastMessageDateSent field in chat dialog
01-07 11:29:06.686 26084-26084/com.om.sigmatech.dating D/QBASDK: Can't parse lastMessageUserId field in chat dialog
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.quickblox.chat.QBGroupChat.leave()' on a null object reference
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.quickblox.chat.model.QBChatDialog.leave(SourceFile:768)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.om.sigmatech.dating.MatchNotificationActivity$5.onSuccess(MatchNotificationActivity.java:313)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.om.sigmatech.dating.MatchNotificationActivity$5.onSuccess(MatchNotificationActivity.java:306)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.quickblox.auth.session.Query.notifySuccess(SourceFile:447)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.quickblox.auth.session.Query$VersionEntityCallback.completedWithResponse(SourceFile:483)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.quickblox.auth.session.Query.completedWithResponse(SourceFile:307)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at com.quickblox.core.server.HttpRequestRunnable$1.handleMessage(SourceFile:43)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at android.os.Looper.loop(Looper.java:148)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5417)
01-07 11:29:06.704 26084-26084/com.om.sigmatech.dating W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
01-07 11:29:06.705 26084-26084/com.om.sigmatech.dating W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
01-07 11:29:06.705 26084-26084/com.om.sigmatech.dating W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
01-07 11:29:06.705 26084-26084/com.om.sigmatech.dating E/MatchNotification: onSuccess: Groyup=Attempt to invoke virtual method 'void com.quickblox.chat.QBGroupChat.leave()' on a null object reference