I have seen this question, and have some more doubts regarding creating a jar file which I can distribute and can be used in any android applications.
What my requirement is
As I said, I want to build and distribute a closed source library. I
don't want the source code to be visible.
In that library I don't want to use any assets, layouts, resources
etc. But I want to use some android specific codes, like getting
android device id.
The most popular answer in the above linked SO question tells to create a regular java project and import android.jar in it. I tried to do that, but I don't know how to add android.jar to any java project. I would like to get some clarification on that too.
Moreover I would like to know if there are any other methods using android sdk itself (without using java project) create a closed source library jar file.
I think what I want is possible, since google analytics for android native apps seems to have done it. I am sure in the .jar file they distribute they are using android specific codes, since there seems no other way for them to get the device information to display in the analytics viewer.
EDIT : CAN SOMEONE CLARIFY THIS??
I think I have made some progress. This is what I have done
Created a regular android project (not library project, the "is
Library" checkmark is unchecked)
In the project I have coded out my logic. It uses some android
specific classes like SharedPreference, UUID, PackageManager. But
nothing related with assets, layouts also no class extending
Activity. Just a java class extending java.lang.object
Exported the project using Project->rightclick->export->Java->JAR
file. In the next screen I unchecked the checkbox near
AndroidManifest.xml. Set a destination directory to export and
clicked next thrice with keeping the default settings. Then I clicked
Finish, and got a lovely libMyLibraryName.jar at my desktop.
Then I created another android project, added this libMyLibraryName.jar to new project using project->rightclick->properties->java build path -> libraries->add external jar.
And I tried to use my class in the library, in my new project
MyLibraryClass objClass = new MyLibraryClass(this);
And I was able to compile and run successfully. I even sent the library to one of my co worker who was able to use the library in his on machine (Just making sure library project in my workspace wont influence the project using it).
Now I have 2 questions.
1) My first question is , what they meant by the term "true library" in the below given documentation ? Is it any non android java project which can be exported to a JAR file?
However, a library project differs from an standard Android
application project in that you cannot compile it directly to its own
.apk and run it on an Android device. Similarly, you cannot export
the library project to a self-contained JAR file, as you would do
for a true library. Instead, you must compile the library indirectly,
by referencing the library in the dependent application and building
that application.
Well this portion is taken from documentation under title "Library Projects".
2) My second question is, anything wrong with the way I have created the JAR file? Any possible pitfalls which might bite me back later? I would like to make sure I am not doing something terribly wrong, before using it in my important projects.
I might add that I didn't try the method of creating a JAVA project and importing android.jar. I am ready to try that one, if what I have done currently is wrong.
The android.jar will be located where you installed your Android SDK. Under the platforms directory there should be a number of other directories named android-<version>. The android.jar will be there. Choose the one specific to the minimum android version you are targeting.
Once you have that, copy it into your project. If you're using eclipse I think you can just cut and paste jars straight into your project, right click and add it to build path. If you're not using eclipse or any other IDE, you just need to ensure that the android.jar is on the classpath when building your jar file.
After that your newly built android library can be dropped into any Android project.
In answer to your additional questions:
What they mean by a true library is a jar file as opposed to an Android library project.
I don't think there's anything wrong with the way you created the jar file. I would have made it using the android.jar as I mentioned above but your way should also work. To verify this I would examine the jar contents and make sure all you have in there is .class files.
Related
Background
I'm working on an app that has become very popular, so much that a part of it is supposed to become an SDK (which would be available for developers), and the app will split to 2 apps (both use the SDK).
According to what I know, there are multiple ways to create an SDK module (previously called "project" on Eclipse) :
Completely open sourced (Android library) - all sources and resources are open sourced and can be modified. An example might be Facebook's SDK and a lot of Github repos.
a single Jar file, which can be closed sourced.
The problem
Sadly, I can't make the SDK open sourced, and it should relatively be protected vs prying eyes (obfuscated etc...).
The issue here is, the SDK needs to use some resources of its own (drawables, strings,...), and so far (because I didn't have a lot of experience with creating SDKs) I've found 2 ways to handle resources for SDKs :
use reflection and/or "context.getResources().getIdentifier" . This is quite messy, as I lose the whole "R" usage of the code. Also, it has issues with "styleable" , as I've written here. It also makes it hard to find unused resources.
even worse ways: put resources in assets folder, put files in a wacky way inside the jar file, ...
Note that a part of the SDK includes custom views (for example, classes that extend from TextView), so even if I do split the SDk into 2 modules- resources and java files, both might have issues of dependencies (each uses the other one).
The question
Is it possible to somehow solve this issue?
Is it possible for the code part of the SDK to remain closed sourced, reach the "R" file as usual, and make it easy for both me and whoever use the SDK ?
How would I then generate the jar file as being obfuscated via Android Studio? and is it possible to prepare it to to be used via gradle afterwards?
Can I maybe make the Android-library of the SDK into an obfuscated jar file and not worry about the "R" file ? I ask this because this way I could enjoy both worlds: for our apps, it would remain open sourced, and for third party apps it would be closed sourced.
EDIT: seeing that this is supposed to be easy, I've tried it myself. I've created a totally new POC project which has an Android library module called "sdkmodule", and added this class to it:
public class SdkClass
{
public String doIt(Context context)
{
return context.getResources().getString(R.string.app_name);
}
}
Then, I've made the app's module to use this one, and I wrote this code in it:
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SdkClass sdkClass=new SdkClass();
Log.d("AppLog","string from SDK:"+sdkClass.doIt(this));
Log.d("AppLog","string with same ID name from app:"+getResources().getString(R.string.app_name));
}
What I expected is that the first log would print the string that's in the SDK module, and the second to show the string of the current project, but instead I got an exception:
java.lang.NoClassDefFoundError: Failed resolution of: Lcom/example/user/sdkmodule/R$string;
On another try, I've got the same string that's used on the app itself (the one that uses the SDK module). And, on another run, the SDK produced the needed string as I've wanted.
How could it be? What should I do ?
In addition, I've tried to make a second activity in the SDK itself, and I've created a resource there that has the same resource name (used for a textView in its layout) as of the app itself, yet with a different value, yet when I've reached this activity, I've seen the one used by the app.
Here's the project, zipped (ignore the name of the folder, I wanted to try flavors too) :
https://drive.google.com/file/d/0B-PZZGk2vPohX25WUDNKTmotUTg/view?usp=sharing
The answer to your problem is to package and distribute your library as an AAR bundle
This format allows you to provide an obfuscated SDK jar and with its resources and the R mapping file.
This format is a standard and fully supported by maven-android-plugin (actually it's the replacement of the old APKLib format which supports only the distribution of source files).
Of course it's also supported by Gradle and Android Studio.
The Android Archive (AAR) format does what you want. It's like an Android-specific JAR file and contains compiled code, but includes its own resources and manifest. You can also include obfuscation as part of the build process. By default, the current version of Android Studio (1.2) and Gradle automatically build .AAR files for all library modules you create in your project.
You can change an app module into a library project that will publish an AAR file just by changing apply plugin: 'com.android.application' into apply plugin: 'com.android.library' in your module's Gradle file. The .AAR file will be placed in your MODULENAME/build/outputs/aar folder after each build. Some more information is available here.
Edit 1, after question updated:
The resources in your AAR get consolidated with the app module when the final APK gets compiled. The app resources will override the library's. This is probably by design, to allow people using a 3rd party library to customize its resources when creating their app, without having to rebuild the library. I think the easiest way to solve your resource conflict issue would just be to name your sdkmodule resources something more unique. Why not make the string key R.string.com_example_sdk_name or something?
No, the AAR libraries don't get obfuscated by default, but you can set up ProGuard in the Gradle build file for your AAR library to take care of this. Other tools are also available.
I have started working on a project where I will need to share a bunch of Java classes across a bunch of apps. In Eclipse it was possible to create one project with all such classes and use it as a library in a workspace with all your dependent projects, but in Android Studio it doesn't seem possible to do so (At least not easily).
I have been reading a bunch of posts and a lot of them suggest setting up a library project, generating an aar file and then using that in my projects. But, as I understand it, this will make my library open-source (Am I right?), which I don't want. I am doing this for a client and I want the code base to be private.
Also, I know that a module can be imported into a new project. But this creates a COPY of the original module. This is not what I want at all. I don't wanna maintain multiple copies of the same classes, which completely defeats the purpose of 'code sharing'.
Is there any good way of achieving what I am looking for? Any help is appreciated.
You have a couple different options.
One option is to maintain your libraries as separate projects and compile them to an archive format, such as JAR or AAR; JAR files are for pure Java libraries, and AAR is for Android libraries (which contain code that accesses Android APIs and/or has Android resources). As was pointed out in the comments, AAR doesn't force you to publish your code to the world any more than JAR files would; it's just an archive file format whose files can be local to your machine or your organization.
With that archive file in hand, you can include it in other projects. If you're part of a multi-developer organization, you may find it convenient to use a repository manager to publish and maintain those libraries within your organization, and you can use Maven coordinate-style specs to include libraries in your projects, which you don't have to manually copy over to your development machine.
The disadvantage of this approach is that it makes it a little harder to make changes to those libraries: you need to load up the project, make changes, build an archive, and distribute the archive.
The other approach is to keep the library as a source module like you did in Eclipse. You observed that Android Studio will make a copy of the module if you import it via UI, but if you bypass the UI and modify the build scripts directly, you can do what you want, which is to use the module in-place and share a single copy among multiple projects. To do this, work in your settings.gradle file and add this:
include ':module_name'
project(':module_name').projectDir = new File(settingsDir, '../relative/path/to/module')
I would strongly encourage you to not use a pure relative path here; in this example, the path is anchored to the settingsDir variable supplied by Gradle, which is defined to be the directory where settings.gradle is found. If you use a pure relative path (i.e isn't anchored to anything), you're dependent on the working directory being the same in all environments where the build file is run (command line vs. Android Studio vs. CI server), which isn't a good thing to assume.
You need to think in the eclipse projects as Android Studio/IntelliJ Idea modules. Then, you can generate android (or java) libraries and then include them in your project.
To mark an Android Studio module as a library you can go to File -> Project Structure -> Facets and there click on Library Module
I was in same situation as you, and i founded an approach using git.
Steps to do, to have library:
Create project in Android Studio.
Create android library module in that project.
In that library module create git repository.
Add modulename.iml in .gitignore file
Use GitHub or Bitbucket for private cloud repository. and push your library to it.
Create new android library model in any project that you want.
Close Android Studio (not sure is that mandatory).
Using explorer go to your created module folder.
Remove all data in it, except modulename.iml.
Clone your library from "GitHub" into it.
That's all.
Now you are able to use library in multiple project whether you are at home or at work. Just after finishing you work not forget to push library changes. And after opening new one pull them.
I think you can automate this thing somehow.
The benefit is that you don't need to build any jar, or aar.
You can certainly create and use a library without making it open source or available to others.
First, you don't need to make it an aar unless it contains Resources.
If it's just plain classes, you can just make it a .jar file.
Either way, the easiest way to share these libraries (either aar or jar) is to set up your own repository. Nexus and Artifactory are the two most common repository managers.
You keep the library in its own project, and then publish it to your own, in-house repository.
Then, projects that need to use the library are configured (in gradle) to use the in-house repository, and get the library from it.
I am working on a Android app in which I would like to add plug and play module functionality ,Say I have Two android project
[A] An app for capturing a image using camera and storing it in memory
[B]Enabling map and locate current location .
now I want to add add this functionality in my Another Android app.While going through android developer link and Android Library Projects - Tutorial I figure out that to use plug and play module I have to make my above project as library project so that I can use it in my new app ,now my questions are
1 Is this only way to use library project to add plug and play module
functionally in my app or there are another way also?
2 what are the pros and cons of using library project in order to add
plug and play module functionally?
basically I am researching on how to add plug and play service in my android app and trying to find best solution ,so any clarity on this topic will be extremaly helpful !!!
thanks in advance !!!
An alternative would be to use a linked source folder. In Eclipse, you can set this up in the project settings in the Java Build Path section. You can choose some source code directory outside your project that will virtually be in your project's space (and other projects that use it will do the same). I find this to be handy just from an IDE UI standpoint when I'm co-developing a module along with an app or two. What I don't like about library projects is that they sometimes don't update correctly within your project so you have to rebuild it and your project or clean your project to continue. Also, the module is simpler because it's just a directory of source code files, not an entire Eclipse project.
One other downside of libraries is that they can introduce conflicts that can be a headache to fight. For example, your library might have a different version of the Android compatibility library in it than your main project, and therefore give you compile time errors. Or there are sometimes errors with duplicate libraries, and you have to go fool with the Order and Export settings of your project.
If your module is going to rely on String, layout, and image resources, etc. that are common to all apps that implement the module, then a library project will be easier to work with so you don't have to pass all your resources in through your module's class constructors and duplicate them in each project.
A third option is Gradle, although as far as I know, that would essentially just help automate one of the above two options. I'm not very familiar with Gradle.
I'm just getting started in Android development, and use Netbeans with NBAndroid and SDK 17.
I'd like to use the same Java source code in my Java and Android app.
http://developer.android.com/guide/developing/projects/projects-eclipse.html says how to do it in Eclipse (although it is sketchy on the .JAR connection thing), but I can't seem to make it work in NB.
Based on that link, My understanding is that the correct setup for the Android app is an Android Application project which references an Android Library project which in turn references a .JAR library produced by a Java Library project. I could then also have a Java Application project referring to the same Java Library project.
So, I've set up this project structure... I have an AndroidApp project which is a basic HelloAndroid Activity in a com.ex package. This project includes an AndroidLib library project in the Libraries folder. I also have a LibClass.java file which defines a simple LibClass class which has one function getText() that just returns a String to be displayed. The MainActivity in the AndroidApp calls this to get the String to output.
When I put LibClass.java directly into the AndroidLib project, everything is fine.
But what I want to do is to share the source code with Java.
So I want to move the LibClass.java into the JavaLib library, whose .JAR file is included in the AndroidLib project. However, when I tried that, I get an error in the MainActivity class, complaining it can't find LibClass. Looking at the Projects window, I can see LibClass.class inside the com.ex package in the JavaLib.jar in the Libraries folder of the AndroidLib project. And AndroidLib is visible in the Libraries folder of the AndroidApp project, but it doesn't show any packages or other contents there.
So I feel like I'm just one step away from making this work. Do I need to do something with one or other of the AndroidManifest files perhaps? Or do something with the build.xml files? Or am I on the wrong track altogether?
I'd be really grateful if someone could post a how-to for this.
I'm trying something similar; I've got Java EE projects, built using Eclipse, and I'm trying to utilize some of that code from my Android projects. This should give me a shared codebase rather than a bunch of confusing SVN externals which I've had to endure before.
Rather than creating JAR files I've found that working with the source and building for the platform works best (well, it has been working but I've got a problem with it at the moment). So, what I'm doing is:
c:\MySvnFolderStructure\MyJavaProjectFolder\src\ (and then all the source under that)
c:\MySvnFolderStructure\MyJavaProjectFolder\android\ (and all the Eclipse Android project gubbins)
c:\MySvnFolderStructure\MyJavaProjectFolder\jee\ (and all the Eclipse JEE project gubbins)
The Android and Java EE projects do not have their own src folders, they both link to the src folder in their parent folder. What this means is that each of the Java implementations is building its own byte code version from the source, and using its own external libraries (like the Apache HTTP ones, for example).
Naturally they can't share stuff like awt (as mentioned in another post), but there's plenty of stuff that does cross-over especially if it's core Java classes that are being used.
Also, it's proving a bit tricky writing JUnit tests as there needs to be some duplication of the test code at the moment because the Android ones need extra instrumentation, but I'm working on it.
Also, see this post about relative paths in Eclipse, which means the folders can be checked-out to different places on different machines (like we all do with our version control check-outs) and still be shared.
if I understand your situation correct, you are trying to use a custom java library for both your android and java applications.
For this scenario, you can build the java library first. Instead of adding the java library jar as android library, you can drop the jar directly inside the libs folder of android project and add it to android project's build path.
If you are using ANT scripts for building the java library jar , you can consider adding the source files also as part of jar. This will help you get code assistance when you develop the android part. But this part is purely optional.
The problem is that the Java platform in Android is different from the JDK platform.
In particular, the .JAR library CANNOT refer to anything that is not icluded in the Android platform. An example of things you can't refer to is java.awt.* (except you can have java.awt.fonts).
There is also a difference between JDK String and Android String -- Android does not implement the isEmpty() method.
I am currently working on a Android Project where we are expected to merge our App with 2 more apps from vendors who wouldn't be sharing their code.So just wanted to know Is there any way we could just include there Source code as JAR Files in our project and then include their resources and point to them(I did do it using getResources().getIdentifier("splash", "layout", getPackageName()) But Its still not working ?? I think I have tried all possible methods so hoping you guys could help me with this.
To quote CommonsWare from this question:
Bear in mind that your packaged classes cannot reference resources (at
least not via R. syntax), and that JARs cannot package resources,
manifest entries, etc. If all you are trying to JAR up is pure Java
code (perhaps using Android APIs), then you should be fine.
Basically, you can only use JARs that contain pure java as libraries in your app, not entire other projects.
The Activities can be compiled into a jar and added to the main Android project and we need to add their project's resources into your Project. The only we could make it work is using the getResources().getIdentifier("splash", "layout", getPackageName()). Even the Widgets like TextView, Button and all those should be referred to using the getResources() method. Like, for example, If you want to perform a action on particular button then we need to identify them by getResources().getIdentifier("Button" /*id in the XML File*/, "id"/*type*/, getPackageName()).
One more thing: you need to specify all the Activities in your Main Android Project's AndroidManifest.xml file with their package name. I hope this solves something.
In order to support faster build times, the r16 tools are creating their own jar files inside of Android Library Projects. You can use this feature to solve this issue. If a vendor would like to release their Android Library Project but without source code, they can make a copy of that Android Library Project that contains everything except for the source code tree. Next, include the jar file from the original Android Library Porject (the one that the r16 tools built.) This will allow you to have a component you can distribute that does not require source code. The consumer of this new Android Library Project will need to manually add any necessary meta data to their own project's AndroidManifest.xml file as needed (Activities, Providers, Permissions, etc).