i need to open a pdf file from my android app. I have the pdf saved in the app package folder (/data/data/com.app.example/files). I have installed in the android emulator the ad
This is because the PDF file resides in your own package and Adobe reader trying to access PDF file from your package which is not allowed for Android application development.
You can try to save file on SDCARD and then open it
Don't use the direct path to access files in application's private to your application. Instead use
FileOutputStream fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);
Refer: http://developer.android.com/guide/topics/data/data-storage.html#filesInternal