/data directory in android is empty. I have installed a few applications and i also wrote code to create a file in /data/Myapp directory ,
I have these lines in OnCreate
On real device, you can't see these folders if it's not rooted. see this question.
If you want to write files in your app directory, then your code is OK. You can check that it is there in the same way you created it - from your application:
File myFile = new File(getFilesDir() + "/test1.txt");
if (myFile.exists())
{
//Good!
}