检查互联网连接（警报对话框）

Question

我有一个应用程序，在第一个检查互联网

然后使用JSON获取数据。

我的问题：当我使用此代码进行检查时，网络结果会崩溃！

但如果我在新项目中使用此代码，它将起作用！ ：|

public void ShowAlertDialog() {
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);
    alertDialog.setTitle(R.string.title);
    alertDialog.setMessage(R.string.message);
    alertDialog.setIcon(R.mipmap.ic_launcher);
    // Setting Positive "Yes" Button
    alertDialog.setPositiveButton(R.string.yes,
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                    new NetCheck().execute();
                }
            });
    // Setting Negative "NO" Button
    alertDialog.setNegativeButton(R.string.no,
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    // Write your code here to invoke NO event
                    finish();
                }
            });
    // Showing Alert Message
    alertDialog.show();
}


/**
 * Async Task to check whether internet connection is working.
 **/

private class NetCheck extends AsyncTask<String,String,Boolean>
{
    private ProgressDialog nDialog;

    @Override
    protected void onPreExecute(){
        super.onPreExecute();
        nDialog = new ProgressDialog(MainActivity.this);
        nDialog.setTitle("Checking Network");
        nDialog.setMessage("Loading..");
        nDialog.setIndeterminate(false);
        nDialog.setCancelable(true);

        nDialog.show();
    }
    /**
     * Gets current device state and checks for working internet connection by trying Google.
     **/
    @Override
    protected Boolean doInBackground(String... args){

        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo netInfo = cm.getActiveNetworkInfo();
        if (netInfo != null && netInfo.isConnected()) {
            try {
                URL url = new URL("http://www.google.com");
                HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
                urlc.setConnectTimeout(3000);
                urlc.connect();
                if (urlc.getResponseCode() == 200) {
                    return true;
                }
            } catch (MalformedURLException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return false;

    }
    @Override
    protected void onPostExecute(Boolean th){

        if(th == true){
            nDialog.dismiss();
            Toast.makeText(getApplicationContext(), "Your device is connected to internet !", Toast.LENGTH_SHORT).show();
            // new GetData().execute();
        }
        else{
            nDialog.dismiss();
            ShowAlertDialog();
        }
    }
}

并在setContentView

之前的onCreate（）中

try
    {
        new NetCheck().execute();
    }
    catch (Exception ex){
        ex.printStackTrace();
    }

及其我的logcat错误

android.view.WindowLeaked: Activity com.irannezhad.rapcity.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{103c02ae V.E..... R.....I. 0,0-1041,568} that was originally added here
                                                                at android.view.ViewRootImpl.<init>(ViewRootImpl.java:470)
                                                                at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:277)
                                                                at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
                                                                at android.app.Dialog.show(Dialog.java:312)
                                                                at android.support.v7.app.AlertDialog$Builder.show(AlertDialog.java:953)
                                                                at com.irannezhad.rapcity.MainActivity.ShowAlertDialog(MainActivity.java:262)
                                                                at com.irannezhad.rapcity.MainActivity$NetCheck.onPostExecute(MainActivity.java:323)
                                                                at com.irannezhad.rapcity.MainActivity$NetCheck.onPostExecute(MainActivity.java:270)
                                                                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:145)
                                                                at android.app.ActivityThread.main(ActivityThread.java:5940)
                                                                at java.lang.reflect.Method.invoke(Native Method)
                                                                at java.lang.reflect.Method.invoke(Method.java:372)
                                                                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
                                                                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)