title: Why BroadcastReceiver for checking battery status not work without registerReceiver() method to register him?
body: <p>I have this code for the BroadcastReceiver</p>
  
  <pre><code>public class BatteryBroadcastReceiver extends BroadcastReceiver {
      @Override
      public void onReceive(Context context, Intent intent) {
          int level = intent.getIntExtra("level", 0);
          MDIS.info("Battery Level: " + level + "%");
      }
  }
  </code></pre>
  
  <p>And this is my manifest section </p>
  
  <pre><code>&lt;receiver android:name=".BroadcastReceivers.BatteryBroadcastReceiver"&gt;
      &lt;intent-filter&gt;
          &lt;action android:name="android.intent.action.BATTERY_CHANGED"/&gt;
      &lt;/intent-filter&gt;
  &lt;/receiver&gt;
  </code></pre>
  
  <p>Why i should use the registerReceiver() method if i add necessary lines in manifest file?</p>