As a new android developer, I just know how to import the third dependencies made by other android developers.But now ,I write a simple custom view ,including a class : enter image description here and a declare-styleable:enter image description here,for convenience for the future,I want make it to a dependency or a jar.I don't know how to do it.Thanks for your help!
A .jar is a compiled Java bitcode for the jvm. Google android Java compiles into dex and it packed into a .apk. I would be utterly shocked if you could ever use a jar file. In general android apks files contain everything needed to run the app they don't tend to depend on anything else.
You can setup intents to pass things around throughout the larger environment but in general if you need the code for several projects, just include the source to be recompiled. You might be able to directly include a .dex but it would certainly not be preferred.
Related
So, I've got a handful of "Utility" style classes in some of my projects. I'm curious if I can move them to an Android Library Project that contains all or most of my non-app specific glue code (wrappers and interfaces, mostly).
So, my question is what happens to the files I don't need in that library. I know Android Library Projects basically just copy their code into the other project, so if I say use 25% of the code in my "general purpose" library, will my app actually contain the bytecode for all 100%, or does it properly strip it down to only the stuff I need.
I had some issues with unused classes in Proguard in the past, so I'm just once-bitten, twice shy with the ADT now...
Unfortunately, all your projects will grow when the library is getting bigger - even if most contents of that library are not used. I tested it myself by creating an app A and a library L. If L is a library used in A, the classes.dex file (and therefore the A.apk file) is growing if I add more classes - even if they are not used.
To sum up: Right now I would create a basic library for certain things that are small and that may be used by many projects, and create a new library for every new component that is going to be larger and only is used by some projects. A good candidate for a new library would be a new UI component with multiple images defined in the resources. A good candidate for the base library are commonly-used methods and things like file caches, for example. Compiled code is compressed quite heavily for Dalvik, which you can see here. (The whole presentation is actually fun to watch :-)
Edit: If ProGuard is activated, it will also remove unused code for you. The default proguard.cfg is sufficient. It will not run on the (default) debug built, but when the final .apk is compiled. So it actually is possible!
I have used 3 level deep Android library projects successfully though it is kind of a pain. The primary use-case is when there are a set of resources and classes that you want to share across a few projects. Since I use a version control system, I would rather not use symlinks.
Note that Android Library projects also suffer greatly when dealing with resources. ADT will rebuild R.java once for each library, and each R.java will contain a copy of all resource ids from all libraries. The core problem here is that resources are regenerated for the entire project as a whole, and there is no way to "build a jar" for a dependency as would be expected with normal "libraries". We tried integrating with OpenFeint, and had all kinds of hell dealing with libraries and dependencies. I think we ended up just merging all the OpenFeint source and resource files into our own project and ditching the "Library" project as it was offering little value.
Android Library projects are a clunky way of sharing code between projects and have a number of drawbacks. I've found that everything accomplished with a Library project can also be accomplished with symlinks (symlink source into two projects). I've yet to find a usecase where an Android Library project offered something that wasn't easy to replicate with other, less fragile means.
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'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).
I have an Android code base which uses APIs with settings to get different data for several apps. All apps use the same code base but with one or two design tweaks. So how do I re-use the main code base without having to copy the whole Android project each time?
iPhone uses multiple targets in the same project which works well. If android cant do this do I need to compile binaries of the code base in one project and then import into each new app project? If so how? I'm using Eclipse and am an intermediate Java developer.
Any help much appreciated!
Doug
Check out "Working With Library Projects" from the Android documentation. This should be just what you're looking for: http://developer.android.com/tools/projects/projects-eclipse.html#SettingUpLibraryProject
The current way to approach this issue if you are using Android Studio with Gradle is by using Gradle, Build Type + Product Flavor
http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Build-Variants
Build Variants
One goal of the new build system is to enable creating different versions of the same application.
There are two main use cases:
Different versions of the same application
For instance, a free/demo version vs the “pro” paid application.
Same application packaged differently for multi-apk in Google Play Store.
This new concept is designed to help when the differences are very minimum. If the answer to “Is this the same application?” is yes, then this is probably the way to go over Library Projects.
Note: This answer is basically obsolete now that one can create .aar libraries with resources. It still works, though, and there may be times when the portability of a .jar is desirable, so I'm leaving it here.
Blumer's answer is a good one, and you should definitely look into Android's idea of library projects. However, there is another alternative. If you have a module that contains only Java code, but no resources of any kind (images, layouts, etc.), you can compile it to a .jar file separately and use the resulting .jar in multiple application projects. It works like this:
Create a new Java project in Eclipse (not an Android project) and move the source code of your module there.
If your module references any classes from the SDK, you'll need to add the Android SDK .jar to the project's classpath (Project > Properties > Java Build Path > Libraries > Add JAR).
When your module is ready to use, bundle up its .class files into a .jar. You can do this manually, or you can look around to figure out how to get Eclipse to do it for you.
Copy your module .jar file into the "libs" directory of your app's main project.
Add the module .jar to the project's classpath (again, Project > Properties > Java Build Path > Libraries > Add JAR).
Now you should be able to build multiple apps using the same .jar, while maintaining only one copy of the module's source code.
Depending on your particular situation, this may or may not work any better for you than the standard Android library mechanism. But it's worth considering as an alternative.
The Android documentation recommends another approach if there aren't too many "different APIs" used.
The idea is to use reflection instead of making direction references to the code. Make sure to use optimized reflection instead of lookups every time.
References
http://developer.android.com/training/multiple-apks/api.html
http://developer.android.com/google/play/publishing/multiple-apks.html#ApiLevelOptions
You might want to consider using a source control system like Subversion (or GIT). Keep your most feature complete version in the trunk, and make branches for your separate versions that use different data sources or require minor layout changes, etc.