Question

首先，我看到了两个问题 first second

但它们不同，我使用Async task与服务器端进行通信，除了两种情况外它工作正常如果服务器由于导致我的应用程序崩溃的任何原因而停止，则首先输入一个第二种情况是我连接到网络但此接入点上没有互联网 我的问题是我如何处理此错误以避免崩溃？这是我的代码

    public class news_tab extends Fragment{
    ListView newsLIST;
    String result_news,result_fav;
    String [] Hot_news,newsName1,newsText1 ,agentName;
    int [] Hot_news_id,agent_id;
    int []  fav_id;
    private Context context;
    ArrayList<String> newsName,newsText,agentNamelist;
    public news_tab()
    {

    }
    public news_tab (Context context)
    {

        this.context=context;
        newsName=new ArrayList<String>();
        newsText=new ArrayList<String>();
        agentNamelist=new ArrayList<String>();
    }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.news, container, false);
            rootView.setBackground(Drawable.createFromPath("@drawable/back"));
            newsLIST=(ListView)rootView.findViewById(R.id.newsLV);
            getFavouriteNews();
            news();


            return rootView;
        }
public void getFavouriteNews() {
        new AsyncTask<Void, Void, Void>() {


            @Override
            protected Void doInBackground(Void... voids) {
                try {
                    if(isNetworkAvailable()) {
                        HttpRequestSender http = new HttpRequestSender((Activity) context);
                        result_fav = http.SEND_POST_get_news_fav("**********/dal/login.asmx/getdata_newsfav");
                    }
                    else
                    {
                        result_fav="";
                        Toast.makeText(context,"Check the internet Connection",Toast.LENGTH_SHORT).show();
                    }
                    //  result = http.SEND_Check("******/Login?email="
                    //      +username.getText().toString()+"&password="+password1.getText().toString());

                    Log.d("String", result_fav);


                } catch (Exception e) {
                    e.printStackTrace();
                }
                return null;
            }

            @Override
            protected void onPreExecute() {



                super.onPreExecute();
            }

            @Override
            protected void onPostExecute(Void aVoid) {

                if(result_fav.contains("text_news")) {

                    //   x.cancel();
                   // Toast.makeText(context, "Welcome Favourite", Toast.LENGTH_SHORT).show();
                    // JSONObject jb = null;
                    try {
                        JSONArray JA = new JSONArray(result_fav);
                        ArrayList <String> newsName , newsText,agentNamelist,urlList;

                        fav_id= new int [JA.length()];


                        for (int i = 0; i < JA.length(); i++) {
                            JSONObject JO = (JSONObject) JA.get(i);

                            fav_id[i]= (int)   JO.get("news_id");


                        }

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }

                }
                else
                {
                   // Toast.makeText(context,"No News",Toast.LENGTH_SHORT).show();

                }
                super.onPostExecute(aVoid);

            }
        }.execute();

    }
    private boolean isNetworkAvailable() {
        ConnectivityManager connectivityManager
                = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        return activeNetworkInfo != null;
    }

最后我得到了错误

03-29 10:15:45.500 24585-24585/com.Offferly.ahmad.hakimi E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.Offferly.ahmad.hakimi, PID: 24585
java.lang.NullPointerException
   at com.Offferly.ahmad.hakimi.tab.news_tab$2.onPostExecute(news_tab.java:217)
   at com.Offferly.ahmad.hakimi.tab.news_tab$2.onPostExecute(news_tab.java:179)
   at android.os.AsyncTask.finish(AsyncTask.java:632)
   at android.os.AsyncTask.access$600(AsyncTask.java:177)
   at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
   at android.os.Handler.dispatchMessage(Handler.java:102)
   at android.os.Looper.loop(Looper.java:146)
   at android.app.ActivityThread.main(ActivityThread.java:5692)
   at java.lang.reflect.Method.invokeNative(Native Method)
   at java.lang.reflect.Method.invoke(Method.java:515)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
   at dalvik.system.NativeStart.main(Native Method)
03-29 10:15:45.540 2952-20003/? E/WakeLock: release without a matched acquire!

Answer 1

您无法在doInBackground（）方法中显示Toast。如果你想这样做，请使用下面的代码。

runOnUiThread(new Runnable() {
    public void run() {
       Toast.makeText(<your class name>.this, "Cool Ha?", Toast.LENGTH_SHORT).show();
}});

试试这个。

Answer 2

如果服务器由于任何原因导致您在 result_fav 变量中获得空响应而停止。您需要在onPostExecute（）方法中处理null 像这样

如果（！TextUtils.isEmpty（result_fav））{

//你的代码

}否则{

//显示吐司无响应

}
第二种情况：

在doInBackground（）方法中删除Toast消息。不能在doInBackground（）方法中显示toast msg

您可以在getFavouriteNews（）方法中尝试：

if(isNetworkAvailable()) {
  //then call your async task                      
}

else
{
  //Show Toast no internet                      
}

Answer 3

从

更改if条件

if(result_fav.contains("text_news"))

到

 if(!TextUtil(result_fav) && result_fav.contains("text_news"))

Answer 4

从doinbackground移除吐司。你应该在ui thread.code上运行它，如下所示

     @Override
   protected Void doInBackground(Void... voids) {
          try {
          if(isNetworkAvailable()) {
       HttpRequestSender http = new HttpRequestSender((Activity) context);
result_fav = http.SEND_POST_get_news_fav("**********/dal/login.asmx/getdata_newsfav");
                        }
                        else
                        {
                            result_fav="";


      runOnUiThread(new Runnable() {
            public void run() {
              Toast.makeText(context,"Check the internet Connection",Toast.LENGTH_SHORT).show();
        }});
                        }
                        //  result = http.SEND_Check("******/Login?email="
                        //      +username.getText().toString()+"&password="+password1.getText().toString());

                        Log.d("String", result_fav);


                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    return null;
                }

Answer 5

在onViewCreated中运行AsyncTask，而不是onCreateView。

异步任务使我的应用程序崩溃

5 个答案: