通过microsoft exchange for Android发送电子邮件时出错：java.lang.NullPointerException:format==null

下面是我使用EWS for Android发送邮件的代码

        ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
        ExchangeCredentials credentials = new WebCredentials("user","pass");
        service.setCredentials(credentials);    
        service.setUrl(new URI("https://valid_server/ews/Exchange.asmx"));  


        EmailMessage msg= new EmailMessage(service);
        msg.setSubject("Hello world!");
        msg.setBody(MessageBody.getMessageBodyFromText("Sent using the EWS Java API."));
        msg.getToRecipients().add("myemail");
        msg.send();

然而，它不工作，我得到下面的错误。谁能告诉我这件事吗

 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕      java.lang.NullPointerException: format == null
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at java.lang.String.format(String.java:1799)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at java.lang.String.format(String.java:1777)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.ServiceRequestBase.getEwsHttpWebResponse(ServiceRequestBase.java:936)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.ServiceRequestBase.validateAndEmitRequest(ServiceRequestBase.java:821)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.SimpleServiceRequestBase.internalExecute(SimpleServiceRequestBase.java:46)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.MultiResponseServiceRequest.execute(MultiResponseServiceRequest.java:143)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.ExchangeService.internalCreateItems(ExchangeService.java:463)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.ExchangeService.createItem(ExchangeService.java:534)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.Item.internalCreate(Item.java:215)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.EmailMessage.internalSend(EmailMessage.java:125)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at microsoft.exchange.webservices.data.EmailMessage.send(EmailMessage.java:253)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at com.example.test.MainActivity$EWSOperation.doInBackground(MainActivity.java:61)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at com.example.test.MainActivity$EWSOperation.doInBackground(MainActivity.java:39)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at android.os.AsyncTask$2.call(AsyncTask.java:292)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at java.util.concurrent.FutureTask.run(FutureTask.java:237)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
 02-12 03:26:00.411  18432-18457/com.example.test W/System.err﹕ at       java.lang.Thread.run(Thread.java:818)

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在这种情况下，您能确保通过调用

msg.setFrom（）

检查设置发件人信息是否有帮助吗？@vk239，我仍然收到相同的错误：（EmailAddress EmailAddress=new EmailAddress（）；EmailAddress.setAddress（“MYEMAIL”）；msg.setFrom（EmailAddress）；您是否可以通过调用

msg.setFrom（）

检查设置发件人信息在这种情况下是否有帮助？@vk239，我仍然收到相同的错误：（EmailAddress EmailAddress=new EmailAddress（）；EmailAddress.setAddress（“MYEMAIL”）；msg.setFrom（EmailAddress）；