java.net.UnknownHostException：关闭模拟器后运行Android Facebook应用程序时无法解析主机“graph.facebook.com”

Question

第一次运行应用程序时，我可以看到facebook群组 但是当我关闭模拟器并再次运行我的应用程序时，我得到以下响应。

{Response:  responseCode: unknown, graphObject: null, error: {HttpStatus: -1, errorCode: -1, errorType: null, errorMessage: java.net.UnknownHostException: Unable to resolve host "graph.facebook.com": No address associated with hostname}, isFromCache:false}

我使用以下代码获取Facebook群组：

    Request request = new Request(session, "/me/groups", null, HttpMethod.GET,
            new Request.Callback() {
                @Override
                public void onCompleted(Response response) {
                     //code for displaying groups in list view as response contains groups information

            });
    request.executeAsync();

我是否遗漏了会话处理用例？