Gingerbread and MODIFY_PHONE_STATE

Recently I figured out that google doesn't like apps like Flip4Silence and any other app which silences the ringer or dismiss a call via the hidden methods of TelephonyManager.

The commit comment:

Mark MODIFY_PHONE_STATE permission as signatureOrSystem
This permission isn't needed right now, since there aren't actually any
public APIs that require it.  (There are a few calls in the ITelephony
interface that do, but they're all hidden.)


Since there's no good reason for 3rd party apps to declare it, let's
mark it signatureOrSystem for now.  We can bring it back -- and probably
split it apart into multiple finer-grained permissions -- once we
finally expose full telephony APIs to 3rd party apps (see bug 1043005). 


Bug: 2989096
Change-Id: Idf898d5e12d648a959f622cd815e75597195aa82

As you see, the MODIFY_PHONE_STATE permission is now a "system only" permission in gingerbread which stops any dismiss call app from working. It's nice that they want to rework the phone api for 3rd party apps but this should happen befor the unofficial reflection way is blocked...

getSystemService() calls are nearly free

Random fact of the day: calls to Context.getSystemService(servicename) are close to be free of overhead if they are called multiple times in the same program.

I had a look into the source of the ContextImpl class where mostly code like this is used to return services:

private AlarmManager getAlarmManager() {
synchronized (sSync) {
if (sAlarmManager == null) {
IBinder b = ServiceManager.getService(ALARM_SERVICE);
     IAlarmManager service = IAlarmManager.Stub.asInterface(b);
       sAlarmManager = new AlarmManager(service);
    }
  }
    return sAlarmManager;
}


So it's nearly free to request a systemservice multiple times which comes handy when you need to pass multiple managers around in your program. You don't have to pass them into every class, the context is just enough.

This creates a nice interface for the caller as he doesn't need to know and/or create all the objects you need. All he knows is that you need a Context which enables you to freely change your implementation at any given time without changing your interface.

How to write a mail with an attachment on Android

Creating a mail on Android which the user may send with the app of his choice is widely spread on the net. But it isn't how you attach a file which will be send by googlemail.

The problem here is that the gmail app only want to send files which are located on the sdcard


Intent mail = new Intent(android.content.Intent.ACTION_SEND);
mail.setType("application/octet-stream");
mail.putExtra(android.content.Intent.EXTRA_EMAIL, new String[] {"my@mail.com"});
mail.putExtra(android.content.Intent.EXTRA_SUBJECT, "Subject");
mail.putExtra(android.content.Intent.EXTRA_TEXT, "Message");
mail.putExtra(android.content.Intent.EXTRA_STREAM, Uri.parse("file://" + Environment.getExternalStorageDirectory().getAbsolutePath() + "/file.txt"));
PrefAct.startActivity(Intent.createChooser(mail, "Send mail via..."));


As said gmail will refuse your attachment when the user sends the mail when the file isn't located on the ExternalStorage.