在android中運行BroadcastReceiver時出現運行時異常？

我試圖執行一個AsyncTask時，無線網絡更改或開關開關，但是當我運行應用程序並更改WiFi網絡時，我得到了「InstantiationException」。在android中運行BroadcastReceiver時出現運行時異常？

06-12 10:31:59.881 24464-24464/com.poliveira.apps.materialtests E/AndroidRuntime﹕ FATAL EXCEPTION: main 
java.lang.RuntimeException: Unable to instantiate receiver com.poliveira.apps.test.MainActivity$WifiReceiver: java.lang.InstantiationException: can't instantiate class com.poliveira.apps.test.MainActivity$WifiReceiver; no empty constructor 
     at android.app.ActivityThread.handleReceiver(ActivityThread.java:2357) 
     at android.app.ActivityThread.access$1500(ActivityThread.java:141) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1310) 
     at android.os.Handler.dispatchMessage(Handler.java:99) 
     at android.os.Looper.loop(Looper.java:137) 
     at android.app.ActivityThread.main(ActivityThread.java:5041) 
     at java.lang.reflect.Method.invokeNative(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:511) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
     at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.InstantiationException: can't instantiate class com.poliveira.apps.test.MainActivity$WifiReceiver; no empty constructor

在我的Manifest.xml我有以下

<!-- Receive Wi-Fi connection state changes --> 
    <receiver android:name=".MainActivity$WifiReceiver"> 
     <intent-filter> 
      <action android:name="android.net.conn.CONNECTIVITY_CHANGE" /> 
     </intent-filter> 
    </receiver>

在MainActivity，我用這個類。

public class WifiReceiver extends BroadcastReceiver { 

    @Override 
    public void onReceive(Context context, Intent intent) { 

     ConnectivityManager conMan = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); 
     NetworkInfo netInfo = conMan.getActiveNetworkInfo(); 

     if (netInfo != null && netInfo.getType() == ConnectivityManager.TYPE_WIFI){ 
      mToolbarSpinnerNavigationItems.clear(); 
      mToolbarSpinnerNavigationItems.add(new SpinnerNavItem("Select your Device", R.drawable.deviceonline)); 
      mArrayAdapter = new ArrayAdapter(MainActivity.this, R.layout.list_item_title_navigation,mToolbarSpinnerNavigationItems){ 
       @Override 
       public View getView(int position, View convertView, ViewGroup parent) { 

        convertView = View.inflate(MainActivity.this, R.layout.list_item_title_navigation, null); 
        // get view 
        TextView tvText1 = (TextView) convertView.findViewById(R.id.devicetitle); 
        ImageView imgIcon = (ImageView) convertView.findViewById(R.id.deviceicon); 
        imgIcon.setVisibility(View.GONE); 
        //imgIcon.setImageResource(mToolbarSpinnerNavigationItems.get(position).getIcon()); 
        // set content 
        tvText1.setText(mToolbarSpinnerNavigationItems.get(position).getTitle()); 
        // return 
        return convertView; 
       } 

       @Override 
       public View getDropDownView(int position, View convertView, ViewGroup parent) { 
        // implement the same way as getView() method 
        // inflate layout 
        convertView = View.inflate(MainActivity.this, R.layout.list_item_title_navigation, null); 
        // get view 
        TextView tvText1 = (TextView) convertView.findViewById(R.id.devicetitle); 
        ImageView imgIcon = (ImageView) convertView.findViewById(R.id.deviceicon); 
        imgIcon.setVisibility(View.GONE); 
        //imgIcon.setImageResource(mToolbarSpinnerNavigationItems.get(position).getIcon()); 
        // set content 
        tvText1.setText(mToolbarSpinnerNavigationItems.get(position).getTitle()); 
        // return 
        return convertView; 
       } 


      }; 

      //setting adapter to Spinner 
      mToolbarSpinner.setAdapter(mArrayAdapter); 
      new selectingDevices().execute(); 
     } 

     else { 
      Log.d("WifiReceiver", "Don't have Wifi Connection"); 
      AlertDialog.Builder builder1 = new AlertDialog.Builder(MainActivity.this); 
         builder1.setTitle("Wifi not enabled"); 
         builder1.setMessage("Please turn on your phone wifi"); 
         builder1.setCancelable(true); 
         builder1.setPositiveButton("Ok", 
           new DialogInterface.OnClickListener() { 
            public void onClick(DialogInterface dialog, int id) { 
             dialog.dismiss(); 
            } 
           }); 
         AlertDialog alertDialog1; 
         alertDialog1 = builder1.create(); 
         alertDialog1.show(); 
     } 

    } 
}

這是從AsyncTask繼承的類。這也在MainActivity類中。

private class selectingDevices extends AsyncTask 
{ 

    @Override 
    protected Object doInBackground(Object[] params) { 
     if (!isCancelled()) 
     { 
      startBonjour(); 
     } 

     return null; 
    } 

    @Override 
    protected void onCancelled(){ 

    } 
}

來源

2015-06-12 Nuwan Indika

我認爲您必須瞭解如何爲信息擴展asynctask http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html –

thnx。這不是asynctask的問題。當WiFi改變應用程序將例外WifiReceiver類。那個班正在給予例外。 –

既然你BroadcastReceiver是一個內部類的MainActivity，所以要WifiReceiver靜態內部類。

public static class WifiReceiver extends BroadcastReceiver { 
....... Your code. 
}

但是，如果您想要使用非靜態內部類，您不能通過AndroidManifest.xml來完成此操作。但是，您可以動態註冊BroadcastReceiver：Receiver as inner class in Android

來源

2015-06-12 05:29:04 Kartheek

問題是，我在WifiReceiver中使用的變量不能更改爲靜態。如果更改會影響其他人。 –

然後你可以動態註冊接收器 – Kartheek

@ user3480706是否有效？ – Kartheek

在android中運行BroadcastReceiver時出現運行時異常？

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