Asset path in Android Stuidio

According to Android guideline document, the assets folder is created automatically and is positioned under the root of the project folder.

So the assets folder should be located at <project root>/assets

But according to my experience, I found it is not true, or is partially true.

The path to assets folder varies according to the build system being used. So it could be very confusing and sometimes make things too complicated.


For the very traditional ADT build system, then the assets folder is located at <project root>/assets


For new Gradle build system, it changed the project structure definition, which is slightly different to the ADT one.

Gradle build system requires the assets folder is part of the “source code” so the asset folder should located at <project root>/src/main/assets/.

For more detailed information, check out this document.

Android Studio

In Android Studio (also apply to IntelliJ IDEA), things get a little bit more complicated. The assets path could be configured in project.

Android Studio store this path in project file (*.iml), which is an xml file. In the project file, under the XPath /module/component@name="FacetManager"/facet@type="android"/configuration, there could be a <option> node with name ASSETS_FOLDER_RELATIVE_PATH to descript the path.

<option name="ASSETS_FOLDER_RELATIVE_PATH" value="/assets" />

If the option element with specific name doesn’t exist, please manully create it.


  • Using Eclipse + ADT, place the assets at <project root>/assets

  • Using Android Studio (or IntelliJ) with Ant or Maven, place the assets at <project root>/assets. And set ASSETS_FOLDER_RELATIVE_PATH to /assets

  • Using Android Studio with Gradle, place the assets at <project root>/src/main/assets/. And set ASSETS_FOLDER_RELATIVE_PATH to /src/main/assets. And invoke mergeAssets during build.

Reuse Android built-in Bluetooth Device Picker

Most Android devices support Bluetooth, and most Android ROMs has built-in bluetooth device picker, which is available to other system apps to select a bluetooth device. Theoretically the Bluetooth Device Picker could be reuse in any apps. But for some reasons, the API is not documented, and not published to everyone.

But it is possible to reuse such resources, so I wrote the following code. But due to the using of undocumented API, so it is not garenteed to work on all android devices.

Code is available as Gist

In the code I uses the Android Annotations, but it should be easy to remove the dependency on Android Annotations by adding a constructor to BluetoothDeviceManager that accepts Context.

Android SQLite database requires special table

I’m working on an Android application recently. During the development, our new app inherited a legacy SQLite database that created by a WinCE application.

Android announce that it supports the SQLite database, so we don’t worry about that too much. But when we try to open the legacy database with SQLiteDatabase.openDatabase, it throws exception on our face!

After debugging, we found to open SQLite database with SQLiteDatabase class requires the database to have a special table called android_metadata, which contains the locale information. And SQLiteDatabase yields exception when the table cannot be found.

The table will be created automatically when SQLiteDatabase creates the database, but if the app need to open the database not created by android, some patch is needed.

Here is the script to patch the database:

Patch Database
CREATE TABLE android_metadata (locale TEXT);
INSERT INTO android_metadata VALUES('en-US');