I have some java code (compiles nicely for Android) in a library project (LIB) that I want to use in an another Android project (A).
As LIB's code is unlikely to change much, I opted for adding it as a jar to A. It works fine.
I have another project that is an Android instrumentation project, testing the first Android project (B).
So what we have now is A including LIB as an external jar, and B testing A.
The problem starts when I want to access from B code written in LIB.
From what I see, unless I add LIB as an external jar to B, it refuses to compile (that is, it cannot access the code in the LIB jar that is included in A).
I am reluctant to add LIB as an external jar to B because:
1. It doesn't feel right, and
2. When running the tests it fails with:
java.lang.IllegalAccessError: Class ref in pre-verified class resolved to unexpected implementation
I found Mike's question, but his solution only covers compiling using an ant script, and I currently prefer to use the Eclipse IDE for this project.
Any idea how can I solve this issue?
(In order to remove this question from the "Unanswered" filter...)
The solution is outlined here:
Android Testing: External libraries
The LIB should be exported from A to make it accessible from B.
Related
I am developing first time Android Library Project that have external dependences of different libraries like retrofit and ormlite-android. The problem i am facing right now is when i use my Android Library Project .aar file inside other project the class not found exception occur when run the code. Please can any one guide me how to fix such issues. Do i have to add external libraries reference inside my dependent app ?
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.
I have maybe this not so common setup:
(> = dependency)
Android project > Android library project 1 > Android library project 2
So I have an Android library project which has a dependency to another library project.
When I'm building project in Eclipse everythings works fine but I cannot get my build working with Ant.
First Ant compiles Android library project 2 which generates a classes.jar and puts this file in the bin folder.
Then Ant tries to compile the Android library project 1 but then I'm getting errors becouse it is missing classes from Android library project 2.
Well this is not so weird becouse the jar file is not included in the libs folders.
But in project.properties i've made a dependency to the library project 2 so why does Ant not copy the classes.jar to the libs folders of library project 1?
Well I can think of a solution to use an Ant task to copy the file to the libs folder, but then I have to modify the build.xml which I do not prefer.
** EDIT
The problem is that the R class is missing, when I look in classes.jar this java file does not contain the R class. So my solution would proberly not work.
This behaviour was caused by a change in R17 of the build tools: http://tools.android.com/recent/dealingwithdependenciesinandroidprojects
In a nutshell: R files for libraries are no longer packaged in the classes.jar for that library. However, since the pareent.R for the parent-library (project1 in your example) also contains the resource-references for the 'child' library (project2 in your example), you don't have to refer to the child-R anyway.
Replace all project2.R-import statements in project1 with project1.R import statements and you should be fine.
For ant to compile add dependency in ant.properties.
eg:
android.library.reference.1=../path/to/library
This sounds like a very brittle setup - you may have good reason for this, but could you instead decouple the libraries dependence on each other?
For example; implement a bridge pattern to translate the calls between both libraries, and make the calling Android project attach them. This way, you have no code in either library that depends on the other, and the only project that needs to handle dependency setup is your main project.
One of the main reasons for using a library is to make the code re-usable, this approach ensures someone (you, a colleague, your successor...) could plug in just one library and create their own implementation of the other one.
Here is another good article on applying the bridge pattern in Java: http://java.dzone.com/articles/design-patterns-bridge
Well the problem was that the R class was missing.
So i removed the R class dependency between the two library projects.
I don't know if this is fixable but i think it is bad practice any way.
Without this dependency Ant builds fine.
Old question, but like me, others might be banging their head on this...
The official answer is "it cannot be done", specifically:
At build time, the libraries are merged with the application one at a time, starting from the lowest priority to the highest. Note that a library cannot itself reference another library and that, at build time, libraries are not merged with each other before being merged with the application.
(extracted from the official documentation: "Referencing a Library Project").
Which means that anything goes, as there is no "clean" way to do it with the tools (and dirty methods are in order).
Hope it helps
I've a main project that depends on other Library projects that use external JARS (that are also used in the main project).
Now with ADT17 I have removed from the main project the external libraries that are also used in library projects, because they are automatically inherited from new AD17 Android dependencies (from library projects).
Until here all works correctly. The problem is when I want to create a Test project for the main project. What I do is mark all externals jars and android dependencies as exportable to be inherited in the test project.
But the problem is that Android dependencies although they are market as exportable aren't inherited from the test project and when I run it I get some Link of class X not found... make sure it's in the apk.
I attach an image to make it more clear:
(It's an snapshot from main project libraries. Blue marked ones are correctly inherited and red ones not).
It seems that it was a bug in ADT17 with test projects that depend on external libraries.
Today I've updated to ADT18 and it works correctly without having any lib defined in test project.
According to this SDK guide, unit-testing a Library project can be achieved by creating a standard application project, reference the Library project and then instrument the application for unit testing.
However, when I do this and launch the test application I get the message
No tests found with test runner 'JUnit 3'.
I'm using Eclipse and the Android ADT plugin, all latest versions.
Note: the projects compile just fine. The test project also installs fine to the emulator. But in the console I can see that it looks for <library>.apk, which of course doesn't exist since I'm compiling this as a library into the test project.
Anyone got this to work? And if so, what is the trickery here?
Update: after discovering and fixing a problem, which was actually including the test classes (!), the test runner now can find all tests. But, all the tests fail with the following exceptions:
java.lang.NoClassDefFoundError: <nameOfClassInLibraryProject>
nameOfClassInLibraryProject are classes defined in the library project. These classes should be compiled into the test project, and indeed, everything compiles just fine. But when running the test project, the runtime doesn't seem to find the library classes.
After much fiddling and wasted time in Eclipse I have managed to get Android Library projects to work.
According to the Working with Library Projects article:
Instead, you must compile the library indirectly, by referencing the library from a dependent application's build path, then building that application.
The problem was that I interpreted this to mean that the library project should be added to the Projects tab in Java Build Path. Doing this makes the test project compile since the library code is obviously available to the compiler. But since the library is not compiled into a .jar or .apk in itself, the library classes are never deployed to the device.
The solution is to not add the library project to Projects, rather on the Source tab, add the library /src folder using the Link Source... button. And yes, it is the library src folder, not the library project root, that must be linked into the test project.