出现以下问题.

如果我调用MobileFirst适配器并在该调用返回之前将应用程序放在后台,当我重新激活应用程序时,它会因此异常而崩溃.

ExceptionObject {System.NullReferenceException: Object reference not set to an instance of an object.
   at IBM.Worklight.WLRequest.responseCallback(IAsyncResult asyncResult)
   at System.Net.Browser.ClientHttpWebRequest.<>c__DisplayClass1d.<InvokeGetResponseCallback>b__1b(Object state2)}  System.Exception {System.NullReferenceException}

这种情况发生在我尝试的任何电话上.
有人知道为什么抛出这个异常吗？

其次,我想知道是否有办法取消通话.因此,当我的应用程序停用时,我可以执行此操作.

编辑：添加适配器调用实现

public void getInvoices(IShowAndProceed showAndProceedVM,JObject parameter)
        {
    String myContextObject = "MyAppWP8";
    WLRequestOptions invoicesOptions = new WLRequestOptions();
    invoicesOptions.setInvocationContext(myContextObject);
    WLProcedureInvocationData InvoicesInvocationData = new WLProcedureInvocationData("BillingAdapter","MyInvoicesProcedure");
    InvoicesInvocationData.setParameters(new Object[] { parameter });

    WLClient.getInstance().invokeProcedure(InvoicesInvocationData,new InvoicesInvokeListener(showAndProceedVM),invoicesOptions);
}