從活動類調用方法時，應用程序崩潰

-2

我試圖創建一個應用程序，該應用程序同時使用了Activity類中的MediaButtonReceiver類和方法。爲了讓Activity類代碼運行，我創建了一個MainActivity的新實例，並試圖運行包含我想運行的代碼的方法。後來我發現這是不可能的，那麼最簡單的解決方法是什麼？從活動類調用方法時，應用程序崩潰

MainActivity.java

public class MainActivity extends Activity { 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    ((AudioManager) getSystemService(AUDIO_SERVICE)).registerMediaButtonEventReceiver(new ComponentName(
      this, 
      external.class)); 

    //external main = new external(); 


} 

public void variables(){ //code run when button is pressed in external.java 

    final ToggleButton toggleWF = (ToggleButton) findViewById(R.id.WiFi_toggle); 
    final ToggleButton toggleBT = (ToggleButton) findViewById(R.id.BT_toggle); 
    final ToggleButton toggleNFC = (ToggleButton) findViewById(R.id.NFC_toggle); 
    NfcAdapter mNfcAdapter = NfcAdapter.getDefaultAdapter(getApplicationContext()); 
    WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE); 

    if (toggleWF.isChecked()) { 
     if (wifi.isWifiEnabled()) { 
      wifi.setWifiEnabled(false); 
     } else { 
      wifi.setWifiEnabled(true); 
     } 
    } 

    if (toggleBT.isChecked()) { 
     BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); 
     if (mBluetoothAdapter.isEnabled()) { 
      mBluetoothAdapter.disable(); 
     } else { 
      mBluetoothAdapter.enable(); 
     } 
    } 

    if (toggleNFC.isChecked()){ 
     Class<?> NfcManagerClass; 
     Method setNfcEnabled, setNfcDisabled; 
     boolean Nfc = false; 
     if(mNfcAdapter.isEnabled()) { 
      try { 
       NfcManagerClass = Class.forName(mNfcAdapter.getClass().getName()); 
       setNfcDisabled = NfcManagerClass.getDeclaredMethod("disable"); 
       setNfcDisabled.setAccessible(true); 
       Nfc = (Boolean) setNfcDisabled.invoke(mNfcAdapter); 
      } catch (ClassNotFoundException e) { 
      } catch (NoSuchMethodException e) { 
      } catch (IllegalArgumentException e) { 
      } catch (IllegalAccessException e) { 
      } catch (InvocationTargetException e){ 
      } 
     } 
     else { 
      try { 
       NfcManagerClass = Class.forName(mNfcAdapter.getClass().getName()); 
       setNfcEnabled = NfcManagerClass.getDeclaredMethod("enable"); 
       setNfcEnabled.setAccessible(true); 
       Nfc = (Boolean) setNfcEnabled.invoke(mNfcAdapter); 
      } catch (ClassNotFoundException e) { 
      } catch (NoSuchMethodException e) { 
      } catch (IllegalArgumentException e) { 
      } catch (IllegalAccessException e) { 
      } catch (InvocationTargetException e) { 
      } 

      if (Nfc == false) { 
       //add code here if NFC fails to disable/enable 

      } 
     } 
    } 


} 





}

二等作出新的MainActivity

實例

public class external extends MediaButtonReceiver { 



@Override 
public void onReceive(Context context, Intent intent) { 
    Log.d("Button", "pressed"); 



    MainActivity main = new MainActivity(); 

    main.variables(); 


} 
}

來源

2017-04-27 James Dooney

您無法執行「MainActivity main = new MainActivity（）」。這對Receiver來說是錯誤的。詳細瞭解如何將數據從接收者發送到活動，然後更新您的觀點。 –

讓你的方法靜態

public static void variables(){....}

然後簡單的用它

MainActivity.variables();

來源

2017-04-27 06:25:26

Take instance of activity like this 

<pre> <code> public class external extends MediaButtonReceiver { 

@Override 
public void onReceive(Context context, Intent intent) { 
    Log.d("Button", "pressed"); 

    if(context instanceof MainActivity) { 
     MainActivity main = ((MainActivity)context); 
     main.variables(); 
    } 
    } 
} </code> </pre>

來源

2017-04-27 09:36:05

從活動類調用方法時，應用程序崩潰

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