I have a desktop application that produces resource / data files for my android app. These are XML text files that store instances of my custom data class. These objects are serialized using the Simple XML Serialization library. In my android app, I'd like to instantiate objects from this XML serialization class.
I like to add these xml files to Android Studio so they are included in the APK on device install and are placed, for example, in the private app directory "files", to which getFilesDir() is mapped. I can't find a way to do that.
If I add these xml files to the Android XML resource folder, I need to use Android's XML resource parser, and can not use the Simple XML library.
Any tips? I feel I made a wrong design choice seeing how restrictive the resource bundling is.
Thanks, Kind regards,
Harmen
As per CommonsWare's comment: the solution was adding it to the raw resource folder, then you can access it using:
InputStream xmlExerciseInputStream = getResources().openRawResource(R.raw.myresource);
MyClass myClass = serializer.read(MyClass.class, xmlExerciseInputStream);
I make a research, and I delve deep into Android resources files. According to this link, it says that Android externalize and separate users' resources from the code to allow using
these resources by Ids that will be generated in R.class, here is the text:
Once you externalize your application resources, you can access them using resource IDs that are generated in your project's R class.
(1): Does being the 'res' folder exists means generating the R.java class? In other words, is R.java a representation to "ids" assigned to any values inside 'res' folder?
(2): Is it possible to place my 'layout' or 'string' files in any other folders aside from 'res'?
Is R.java a representation to "ids" assigned to any values inside
'res' folder?
It is most likely the idea of R.java.
Is it possible to place my 'layout' or 'string' files in any other
folders aside from 'res'?
Yes you can do that but before you start make sure you checked the project structure view and not the other options like android structure view.
In your build.gradle
android {
....
sourceSets {
main {
res.srcDirs = [
"src/main/module-res/compose"
];
}
}
}
Then create the desired directory similar to what you have declared.
Here is an example image showing that it will work.
What's good about it is that you can make more res folder (just add it in the array and separate it with comma). Take note that each res folder must have its own drawable, layout etc. folder.
Example:
res.srcDirs = [
"src/main/module-res/compose",
"src/main/module-res/design",
"src/main/module-res/extra"
];
R.java file is an auto-generated file by aapt (Android Asset Packaging
Tool) that contains resource IDs for all the resources of res/
directory. when you create any component in the xml file, id for the
corresponding component is automatically created in this file.
when creating an layout file using android studio it will automatically put it under layout folder, but when you create it manually it will be classified as the parent folder, eg : create layout file under drawable will be called like R.drawable.mLayout, android studio will show it as warning but it will work fine, so yes you can put any type of xml under any folder and it will work fine, put it's easier to classify as default for more readability and clearer architecture
I have been working on a simple android tutorial and while browsing through the project folders I found this R.java file in gen folder...
When I opened it seemed to me as a mess...
first R itself is a class.
it had multiple Inner classes defined within eg drawable,id,layout,etc.
and that inner classes had lots of variables declared as below which were assigned with hex values
public static final int addr=0x7f080003;
...
...
and much more
R is auto generated and acts as some pointer for other files
Questions for R.java
what it is basically for
how it works
why
values are in hex
what role did it performs while the actual application is running
"Acts as some pointer to other files" is actually absolutely correct, now the question is which files it points to how it is done.
What does it contain?
R file contains IDs for all the resources in the res folder of your project and also some additional IDs that you define on your own (in the layouts, for example). The IDs are needed for the Android resource management system to retrieve the files from the APK. Each ID is basically a number which corresponds to some resource in the resource management system.
The file itself is needed so you can access or reference the resource from code by giving the ID of the resource to the resource manager. Say, if you want to set the view in the activity, you call
setContentView(R.layout.main);
main in the R file contains the number which is understood by the Android resource management system as the layout file which is called main.
Why is it better than just plain file names?
It's harder to make a mistake with the generated fields. If you write the field name incorrectly, your program won't compile and you will know that there's an error immediately. If you write an incorrect string, however, the application won't fail until it is launched.
If you want to read more on this topic, you should check the Android documentation, especially the Accessing Resources part.
This holds your resource ids. So when you do something like
TextView tv = (TextView) findViewById(R.id.mytextview);
it looks up your id here for that View, layout, etc... This way the app has an easy way to look up your ids while you can use easy to remember names. Anytime you create a resource it automatically creates an id for it and stores it here. That's why you never want to try and edit this file yourself.
One way to think about how valuable R.java is, imagine a world without it. Its amazing how android brings the xml and java world together to help avoid coding the UI manually completely. With legacy java building UI using the java language was a pain. Invaluable.
With Android you can not only build your UI using only xml, but also see it while you build it. Invaluable.
Every element in the xml can be referenced in the java code WITHOUT writing a single line of code to parse the xml :). Just R.id.nameOfElement. Invaluable.
Rapid development is beautifully done in android. Imagine if iPhone would have 5000 screens to fit that one piece of code, they would crumble on their XCode. Google has done a wonderful job with just R.java. Invaluable.
In the Android SDK documentation, all of the examples used with the #drawable/my_image xml syntax directly address images that are stored in the res/drawable directory in my project.
I am wondering if it is explicitly not okay to create a sub directory within the drawable directory.
For example, if I had the following directory layout:
res/drawable
-- sandwiches
-- tunaOnRye.png
-- hamAndSwiss.png
-- drinks
-- coldOne.png
-- hotTea.png
Could I reference the image of a tuna salad sandwich as #drawable/sandwiches/tunaOnRye
Or do I have to keep the hierarchy flat in the drawable directory.
No, the resources mechanism doesn't support subfolders in the drawable directory, so yes - you need to keep that hierarchy flat.
The directory layout you showed would result in none of the images being available.
From my own experiments it seems that having a subfolder with any items in it, within the res/drawable folder, will cause the resource compiler to fail -- preventing the R.java file from being generated correctly.
The workaround I'm using (and the one Android itself seems to favor) is to essentially substitute an underscore for a forward slash, so your structure would look something like this:
sandwich_tunaOnRye.png
sandwich_hamAndSwiss.png
drink_coldOne.png
drink_hotTea.png
The approach requires you to be meticulous in your naming and doesn't make it much easier to wrangle the files themselves (if you decided that drinks and sandwiches should really all be "food", you'd have to do a mass rename rather than simply moving them to the directory); but your programming logic's complexity doesn't suffer too badly compared to the folder structure equivalent.
This situation sucks indeed. Android is a mixed bag of wonderful and terrible design decisions. We can only hope for the latter portion to get weeded out with all due haste :)
Actually, on Android Studio it is possible. You can have nested resources as shown here :
There is also a plugin to group resources here.
I recommend to avoid this though.
Yes - it does suck :) However you can use the assets folder and have sub directories in there and load images that way.
Use assets folder.
sample code:
InputStream is = null;
try {
is = this.getResources().getAssets().open("test/sample.png");
} catch (IOException e) {
;
}
image = BitmapFactory.decodeStream(is);
I've wrote an eclipse plugin which allows to create virtual subfolder by separating the file name with two underscores __. The project is in early stages, but don't worry it won't crash your IDE
more details can be found here, feel free to fork and send pull requests:
https://github.com/kirill578/Android-Sorted-Res-Folder
I like to use a simple script to flatten an organized directory structure provided by designers to something that can be used to generate an R file.
Run with current path in drawable-hdpi:
#! /bin/bash
DIRS=`find * -type d`
for dir in ${DIRS} ; do
for file in `ls ${dir}` ; do
mv ${dir}/${file} ${dir}_${file};
done
rmdir ${dir};
done
In android studio with gradle you can have multiple source directors which will allow you to separate resources. For example:
android {
....
android.sourceSets {
main.res.srcDirs = ['src/main/extraresdirnamed_sandwiches', 'src/main/res']
}
....
}
However the names must not collide which means you will still need to have names such as sandwiches_tunaOnRye but you will be able to have a seperate section for all of your sandwiches.
This allows you to store your resources in different structures (useful for auto generated content such as actionbargenerator)
One way to partially get around the problem is to use the API Level suffix.
I use res/layout-v1, res/layout-v2 etc to hold multiple sub projects in the same apk.
This mechanism can be used for all resource types.
Obviously, this can only be used if you are targeting API levels above the res/layout-v? you are using.
Also, watch out for the bug in Android 1.5 and 1.6.
See Andoroid documentation about the API Level suffix.
With the advent of library system, creating a library per big set of assets could be a solution.
It is still problematic as one must avoid using the same names within all the assets but using a prefix scheme per library should help with that.
It's not as simple as being able to create folders but that helps keeping things sane...
There is a workaround for this situation: you can create a resVector (for example) folder on the same level as default res folder. There you can add any drawable-xxx resource folders there:
resVector
-drawable
-layout
-color
After that all you need is to add
sourceSets {
main.res.srcDirs += 'src/main/resVector'
}
into your build.gradle file (inside android { }).
This is not perfect methods. You have to implement same way which is display here.
You can also call the image under the folder through the code you can use
Resources res = getResources();
Drawable shape = res. getDrawable(R.drawable.gradient_box);
TextView tv = (TextView)findViewByID(R.id.textview);
tv.setBackground(shape);
Not mine but I found this thread when looking for this issue, if your using Android Studio and Gradle Build system its pretty easy no plugins necessary just a little build file editing
https://stackoverflow.com/a/22426467/618419
Gradle with Android Studio could do it this way (link).
It's in the paragraph "Configuring the Structure"
sourceSets {
main {
java {
srcDir 'src/java'
}
resources {
srcDir 'src/resources'
}
}
}
create a folder in main.
like: 'res_notification_btn'
and create tree folder in. like 'drawable' or 'layout'
then in 'build.gradle' add this
sourceSets
{
main
{
res
{
srcDirs = ['src/main/res_notification_btn', 'src/main/res']
or
srcDir 'src/main/res_notification_btn'
}
}
}
#!/usr/bin/env ruby
# current dir should be drawable-hdpi/ etc
# nuke all symlinks
Dir.foreach('.') {|f|
File.delete(f) if File.symlink?(f)
}
# symlink all resources renaming with underscores
Dir.glob("**/*.png") {|f|
system "ln -s #{f} #{f.gsub('/', '_')}" if f.include?("/")
}
Check Bash Flatten Folder script that converts folder hierarchy to a single folder
assets/
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.
http://developer.android.com/tools/projects/index.html
Subdirectories are not allowed, the resource must contain only [a-z0-9_.].
No you have uppercase letters, and no forward slashes.
It is possible to have multiple drawable folders by having an extra folder parallel to 'res' with a subdirectory 'drawable' and then add following to gradle:
sourceSets {
main {
res.srcDirs 'src/main/<extra_res>'
}
}
Tested with gradle 6.5.1
For anyone using Xamarin (either Xamarin.Android or Xamarin.Forms), there is a way to do this.
In the .csproj file for the Android project find the line for MonoAndroidResourcePrefix (documented, though rather poorly, here). Add the subdirectories you are wanting to use here, separating each entry by semicolons. When building, Visual Studio strips these prefixes so that all of the resources end up in a flat hierarchy. You may need to reload the solution after making these changes.
These directories do not need to be subdirectories of the default Resources directory in the project.
Make sure that files you add are getting the build action set to "AndroidResource".
For Xamarin.Android, the visual editor won't recognize images and will show the error "This resource URL cannot be resolved" but the project will build and the image will be visible at runtime.
Right click on Drawable
Select New ---> Directory
Enter the directory name. Eg: logo.png(the location will already show the drawable folder by default)
Copy and paste the images directly into the drawable folder. While pasting you get an option to choose mdpi/xhdpi/xxhdpi etc for each of the images from a list. Select the appropriate option and enter the name of the image. Make sure to keep the same name as the directory name i.e logo.png
Do the same for the remaining images. All of them will be placed under the logo.png main folder.
To sum up: in order to add easily unit tests for a SAX parser I would like to load XML from a file.
Now, I have my XML in a static string inside my unit test class, but it is not very convenient for large XML.
This is why I would like to add some XML files to my project and load them in my unit test. How can I do this?
This question is tagged as "Android" and I noticed that you mentioned an Activity, so I'm going to assume that you're trying to load an XML file within an Android application. If that is the case, put your XML file under /assets and call:
InputStream is = getAssets().open("input.xml")
from your Activity. From there, you can manipulate it into SAXBuilder. This will only work if you've set up your test to run on the emulator (or if you're just trying to debug outside of a unit test).
SAXBuilder has a constructor to read data from file:
Document build(java.io.File file)
This builds a document from the supplied filename.
http://www.jdom.org/docs/apidocs/org/jdom/input/SAXBuilder.html