Share file between activites

1. Set this same shared user id in manifest

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.a"
    android:versionCode="1"
    android:versionName="1.0"
    android:sharedUserId="com.example.id">
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.b"
    android:versionCode="1"
    android:versionName="1.0"
    android:sharedUserId="com. example.id">

2. Get another app’s context with createPackageContext()

Context otherContext = context.createPackageContext("com.example.a", 0);
AssetManager am = otherContext.getAssets();

http://joshzhchen.blogspot.com/2010/09/android-application-share-user-id.html
http://stackoverflow.com/questions/5493396/how-to-reference-android-assets-across-packages