Difference between res and assets directories

Question

I know that files in the res directory are accessible from R class while assets behaves like a file system  but I would like to know  in general  when it s best to use one and the other  Can anyone help me in knowing the real differences between res and assets

User · Answer

Following are some key points     Raw files Must have names that are valid Java identifiers   whereas files in Assets Have no location and name restrictions  In other words they can be grouped in whatever directories we wish Raw files Are easy to refer to from Java as well as from xml  i e you can refer a file in raw from manifest or other xml file   Saving asset files here instead of in the assets  directory only differs in the way that you access them as documented here http   developer android com tools projects index html  Resources defined in a library project are automatically imported to application projects that depend on the library  For assets  that doesn t happen  asset files must be present in the assets directory of the application project s  The assets directory is more like a filesystem provides more freedom to put any file you would like in there  You then can access each of the files in that system as you would when accessing any file in any file system through Java   like Game data files   Fonts   textures etc  Unlike Resources  Assets can can be organized into subfolders in the assets directory However  the only thing you can do with an asset is get an input stream  Thus  it does not make much sense to store your strings or bitmaps in assets  but you can store custom-format data such as input correction dictionaries or game maps  Raw can give you a compile time check by generating your R java file however If you want to copy your database to private directory you can use Assets which are made for streaming    Conclusion   Android API includes a very comfortable Resources framework that is also optimized for most typical use cases for various mobile apps  You should master Resources and try to use them wherever possible  However  if you need more flexibility for your special case  Assets are there to give you a lower level API that allows organizing and processing your resources with a higher degree of freedom

User · Answer

With resources  there s built-in support for providing alternatives for different languages  OS versions  screen orientations  etc   as described here  None of that is available with assets  Also  many parts of the API support the use of resource identifiers  Finally  the names of the resources are turned into constant field names that are checked at compile time  so there s less of an opportunity for mismatches between the code and the resources themselves  None of that applies to assets   So why have an assets folder at all  If you want to compute the asset you want to use at run time  it s pretty easy  With resources  you would have to declare a list of all the resource IDs that might be used and compute an index into the the list   This is kind of awkward and introduces opportunities for error if the set of resources changes in the development cycle    EDIT  you can retrieve a resource ID by name using getIdentifier  but this loses the benefits of compile-time checking   Assets can also be organized into a folder hierarchy  which is not supported by resources  It s a different way of managing data  Although resources cover most of the cases  assets have their occasional use   One other difference  resources defined in a library project are automatically imported to application projects that depend on the library  For assets  that doesn t happen  asset files must be present in the assets directory of the application project s    EDIT  With Android s new Gradle-based build system  used with Android Studio   this is no longer true  Asset directories for library projects are packaged into the  aar files  so assets defined in library projects are merged into application projects  so they do not have to be present in the application s  assets directory if they are in a referenced library     EDIT  Yet another difference arises if you want to package a custom font with your app  There are API calls to create a Typeface from a font file stored in the file system or in your app s assets  directory  But there is no API to create a Typeface from a font file stored in the res  directory  or from an InputStream  which would allow use of the res  directory    NOTE  With Android O  now available in alpha preview  you will be able to include custom fonts as resources  See the description here of this long-overdue feature  However  as long as your minimum API level is 25 or less  you ll have to stick with packaging custom fonts as assets rather than as resources

User · Answer

Ted Hopp answered this quite nicely   I have been using res raw for my opengl texture and shader files  I was thinking about moving them to an assets directory to provide a hierarchical organization    This thread convinced me not to   First  because I like the use of a unique resource id   Second because it s very simple to use InputStream openRawResource or BitmapFactory to read in the file   Third because it s very useful to be able to use in a portable library

User · Answer

Both are pretty similar  The real main difference between the two is that in the res directory each file is given a pre-compiled ID  which can be accessed easily through R id  res id   This is useful to quickly and easily access images  sounds  icons      The assets directory is more like a filesystem and provides more freedom to put any file you would like in there  You then can access each of the files in that system as you would when accessing any file in any file system through Java  This directory is good for things such as game details  dictionaries    etc  Hope that helps

User · Answer

If you need to refer them somewhere in the Java Code  you d rahter put your files into the  res  directory   And all files in the res folder will be indexed in the R file  which makes it much faster  and much easier   to load them

User · Answer

Assets provide a way to include arbitrary files like text  xml  fonts  music  and video in your application  If you try to include these files as  resources   Android will process them into its resource system and you will not be able to get the raw data  If you want to access data untouched  Assets are one way to do it

User · Answer

Use assets like a filesystem to dump any kind of files  And use res to store what it is made for  layouts  images  values

User · Answer

I know this is old  but just to make it clear  there is an explanation of each in the official android documentation    from http   developer android com tools projects index html  assets   This is empty  You can use it to store raw asset files  Files that you save here are compiled into an  apk file as-is  and the original filename is preserved  You can navigate this directory in the same way as a typical file system using URIs and read files as a stream of bytes using the AssetManager  For example  this is a good location for textures and game data   res raw   For arbitrary raw asset files  Saving asset files here instead of in the assets  directory only differs in the way that you access them  These files are processed by aapt and must be referenced from the application using a resource identifier in the R class  For example  this is a good place for media  such as MP3 or Ogg files

[android] Difference between /res and /assets directories

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