Question

我正在使用排球库。当我尝试向无效域名发送请求时，我的应用程序崩溃，所以我想知道后台发生了什么，我该如何解决这个问题？演示代码可以帮助我。

final RequestQueue reQueue=Volley.newRequestQueue(this);
    final String url="http://www.googkjle.com";  // invalid domain name
    checkbtn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub


            StringRequest request=new StringRequest(com.android.volley.Request.Method.GET,
                    url, 
                    new Response.Listener<String>() {

                @Override
                public void onResponse(
                        String response) {


                        showAlertDialog(MainActivity.this, "INTERNET ACCESS", "You have internet access"+response.substring(0,50));

                }
            },

            new Response.ErrorListener() {

                @Override
                public void onErrorResponse(
                        VolleyError error) {
                    // TODO Auto-generated method stub
                    int a=error.networkResponse.statusCode;
                    showAlertDialog(MainActivity.this, "Ohh. NO INTERNET ACCESS", "You do not have internet access");

                    System.out.println("status code : "+a);
                }
            });

                reQueue.add(request);

        }
    });



}



public void showAlertDialog(Context context, String title,String message) {

    AlertDialog alertDialog=new AlertDialog.Builder(context).create();
    alertDialog.setTitle(title);
    alertDialog.setMessage(message);
    alertDialog.show();

}

LogCat：

08-27 00:37:42.735: D/gralloc_goldfish(2637): Emulator without GPU emulation detected.
08-27 00:37:46.445: D/AndroidRuntime(2637): Shutting down VM
08-27 00:37:46.445: W/dalvikvm(2637): threadid=1: thread exiting with uncaught exception (group=0xb3a03ba8)
08-27 00:37:46.485: E/AndroidRuntime(2637): FATAL EXCEPTION: main
08-27 00:37:46.485: E/AndroidRuntime(2637): Process: com.exampfle.real, PID: 2637
08-27 00:37:46.485: E/AndroidRuntime(2637): java.lang.NullPointerException
08-27 00:37:46.485: E/AndroidRuntime(2637):     at com.exampfle.real.MainActivity$1$2.onErrorResponse(MainActivity.java:78)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at com.android.volley.Request.deliverError(Request.java:563)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:101)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at android.os.Handler.handleCallback(Handler.java:733)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at android.os.Handler.dispatchMessage(Handler.java:95)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at android.os.Looper.loop(Looper.java:136)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at android.app.ActivityThread.main(ActivityThread.java:5001)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at java.lang.reflect.Method.invokeNative(Native Method)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at java.lang.reflect.Method.invoke(Method.java:515)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
08-27 00:37:46.485: E/AndroidRuntime(2637):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

编辑：我误读了行号...修复答案

如果您的MainClass上的第78行是：

int a=error.networkResponse.statusCode;

然后networkResponse可能为null，并导致NPE - 空指针异常

您可以通过以下方式解决此问题：

try{
   int a=error.networkResponse.statusCode;
} catch (NullPointerException e){
   // Dont know... perhaps just put a Toast to show... or
   int a=-1;
}

在Android中将请求发送到无效域名时会发生什么？

1 个答案: