Develop Reference

Developing Android 9.0 eSIM LPA (system app)

Trying to develop android LPA system app for eSIM with the new Pie API.
The doc says to extend the abstract EuiccService class. But this class is not in the official SDK, and the link in the docs just leads to corresponding file in the android source repo.
I tried using this file/class as a dependency, but it references other internal android classes/annotations and causes build/IDE errors.
Does anyone have an idea how to use this?
Do I really have to pull android src code and somehow reference required class from it?
EDIT: I think I've solved it, found couple of potential solutions, but they were a bit cumbersome. Used the android.jar from here: https://github.com/anggrayudi/android-hidden-api (contains modified android.jar with hidden APIs and internal resources). It didn't work when i replaced the whole file and resulted strange build errors, but i manually transferred the android\service\euicc\ folder to original android.jar of android-28 sdk and it works perfectly (class is available and apk builds without issues). And no need to waste time pulling and building AOSP.
EDIT #2: apparently not fully fixable atm. There's issue with android gradle plugins (at least 3.2.x-3.3.x) where during full sync some build task generates mock classes from android.jar and process fails if it's modified (discussion is here: https://github.com/anggrayudi/android-hidden-api/issues/46). Error looks like this:
Failed to transform file 'android.jar' to match attributes {artifactType=android-mockable-jar, returnDefaultValues=false} using transform MockableJarTransform
There's a workaround for that, though inconvenient:
when you need a full sync for the project, replace the android.jar with original, run sync, restore modified android.jar, the IDE now will run indexing and classes will be available again with build working until next full sync.
Will update this post if/when it's fixed or new solution is found.
EDIT#3: here's probably a final solution for EuiccService case (turned out pretty obvious):
Instead of adding 'android/service/euicc' folder to android.jar, just put it in a separate library and add it as a compileOnly dependency. Since the classes were not in the SDK, the lib should not cause conflict (would be the case if you need to use modified framework or access hidden APIs in already existing classes).

If you are going to create a System APP, you will do it in several ways:
You could call a part of the SystemAPI (a method for example) by reference.
You could make the aplication as a part of the AOSP Project (Downloading the AOSP code, and introducing your app as part of packages/apps/)

You will be able to access system APIs on a rooted device or if you have system permissions (this happens when you flash your app into the device as part of the system image).
However, if you want to be able to call the EuiccService class from Android Studio (for coding purposes), you'll need to add the Android framework jar to your project.
The steps are provided below:
First, you will have to download and build AOSP and generate a framework jar for your target Android version. Check the documentation here to get an idea of how to download and build AOSP.
After a successful build all framework classes are compiled into a jar called classes.jar which can be found at the location out/target/common/obj/JAVA_LIBRARIES/framework_intermediates.
Get this classes.jar and add it to your Android project as a jar file.
Gradle sync the project and start coding.
Please beware that you WILL NOT BE ABLE TO run this app on an Adnroid device where you do not have system permission for this app.

gradlew appengineEndpointsInstallClientLibs does not install client libs (but does generate them)

I am working on an android project working in Android Studio (0.5.3).
I have created two endpoint api classes (called UserEndpoint and OfferEndpoint) in the backend part of the project. Then I wanted to create the client libraries to use in the app part of the project. I use the gradlew appengineEndpointsInstallClientLibs command for this. In the /build/client-libs part it did create the .zip files of the client libraries. But it did not install them in the app part of the project.
So now my question:
Is the command I am using (gradlew appengineEndpointsInstallClientLibs) supposed to also install them in the app part, and if yes what could be the reason it is not working for me (there seem to be no errors).
This tutorial mentions that I have to manually add the libraries. I added the .zip files to the /libs folder, but there is no 'add as library' option as the tutorial mentions. Is this the correct way of doing this? And if yes could someone give me a little more in detail explanation because I tried some things by adding the dependency in the build.gradle file but nothing seems to work.
Thanks in advance!

By default, if you don't use #ApiNamespace, the namespace that is used
is the reverse of your-project-id.appspot.com. That is, the package
path will be com.appspot.your-project-id.yourApi.
Source
The annotation was missing in the #Api annotations of the endpoints.

Android library project as jar file for distribution, like google analytics

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.

Sharing Java library with Android Apps

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.

Packaging a jar for Android

I have modularised some simple classes into their own project for reuse elsewhere. These classes typically contain only fields and accessor methods (i.e. nothing Android specific).
They are later packaged up using ant's jar task and stored in a Maven repository.
In an Android project, I've stored said jar file into a libs directory and added to the build path. On running the emulator however, I get a "class not found" exception relating to my package. Other third party libraries (such as GSon) are being picked up fine.
Are there any specific steps required to make a jar file compatible with Android? (This reply seems to suggest otherwise). How can I debug this further?

No as long as you do not need e.g. classes from javax.* that are not in Android. If I were you I would consider looking at using the Android Maven Plugin for your build though. Check out the morseflash example from the official samples collection. It showcases exactly your scenario.

You only need an Android library project if your going to be reusing Android components and resources. In your case, I believe you added the project to the build path, but I'm sure your not exporting it as part of the dependent project.
So open the project properties, open up the Java Build Path options and make sure that you have your JAR selected as an exported dependency in the Order and Export tab.
UPDATE
This is what your entry should read:
<classpathentry exported="true" kind="lib" path="libs/tlvince-dao-0.1.0.jar"/>
I've also forked an updated version of your gist.

This issue was a result of compiling the jar to Java 7. Android does not support Java 7 (yet).
Compiling to Java 6 bytecode by setting target="1.6" in ant's javac task solved the issue.