Develop Reference

Android studio import problems. (Apktool)

I have been trying to import a file to android studio that I decompiled using apktool. But when I try to import the file to Android studio it does not show anything on the "Project" browser. While in the import process, in the first step, I chose "Create project from existing sources". Is there anyway to fix this problem? Also, is there anyway to use in android studio a file from notepad++?
Thanks.

As Daniel Souza replied, apktool is just a tools to help you to extract the class and manifest. If you look into the detail and the flow of the Android build process (https://source.android.com/source/jack.html),
you will know every class will be obfuscated, packed and put it into the .dex file(include your own classes, android support library and other 3-party libraries).
Normally, the .apk file only included the following types of file.
.dex files (it might be not only one if the problem of 65K methods exists)
manifest( Android permission and features meta-data)
asset (Drawable, asset folders, layout and R)
Therefore, when you used apktools and some other tools(j-soup) to do some reverse-engineering. You can only have the source files only. And as Daniel method, you can import the project to the android studio but many errors might be existed into your project.
R.java cannot be generated (since all the custom id value will be converted to be a unqiue integer in the apk., this cannot be reversed as human-readable meaning even you use the apktool)
Obfuscated class and variable name. As I mentioned the process of how the apk built, the class and variable name will be obfuscated after building. Reverse engineering will be difficult to findout the logic inside the application since almost all the name are renamed as (a,b,c,d,e...)
Proguard problem, some application might use advanced technologies to compile the source code using more complex logic flow ( like Dexguard did). After you finish reverse engineering, it will be more difficult to findout the inside logic in the application.
If it is a "Simple" application, you might be able to find out what happen in the obfuscated code.
If it is a "Complex" application including a lot of libraries, it will be disaster if you are trying to dig out the logic inside it.

apktool is a reverse engineering tool that generates the source, but not the gradle build scripts, which is why it does not show up as a project you can open. You have to "import from existing sources" because apktool only generates the source files and Android Studio will attempt to fill in the gradle build files.
Once you import the project, you can add any files you like to your project's directory. This includes ones that you generate from other programs including Notepad++. You can do this in Android Studio with from Project View (Alt+1) with Copy/Paste or Drag/Drop .

Is it possible to make android library contains readme.txt?

I am new in Gradle.
I've been made android library and I will upload this into maven repository.
But is it possible to add "Readme.txt" into my library?
for example,
When someone add my library into dependencies section in build.gradle and sync.
then Gradle creates(or copy) "Readme.txt" into target project(probably $projectDir or $projectDir/app) and user can read it(Like NuGet)
(Important things of this library, how to use example or something like that.)
I think it is really annoying visit project web-site and read "How to use" every using single library.
I want my library contains how to use text file.
Thank you.

I don't think this is possible, you don't know how the calling use is referencing your project. They are likely only referencing the compiled source code and never running your gradle file.
This is not a good idea, you don't know their exact folder structure, and even if you did you can not be sure that your readme.txt would have a unique name that did not conflict with their project file.s

When using a .jar file you cannot include this as resources cannot be compiled into it. But you can export your library as an *.aar file which can contain resource files. You get this by using "com.android.library" as your plugin type and can then find the aar-file in your build folder after you have built it.
This can then be included in your other project e.g. as a file reference.

.jar android library import into Xamarin project

There are several ways that Andorid aka-native code (Java code) could be integrated into Xamarin project. Official ways are listed in this article.
We are trying to use a Java Library Binding approach discribed in the article.
Our test andoid library is published on Github for this question specifically.
We've created it in Android Developer tools setting it as Java Android Library. It is built in Eclipse into a .jar format that tutorial on Xamarin site assumes to be sufficient.
If we are trying to bind .jar into our project in Visual Studio, the Object Explorer will show us the binding asseblie's namespace, but in code, even though the assembly is referenced, we can't access the methods and classes in the namespace, decleared in our test java android lib..
On the other hand, when we take almost any .jar, which is an android library on the internet (for example this one), we can bind it and access it's methods without a problem.
Please compare two .jar and if possible, let me know what is wrong with our test android library on github, that causes our namespace to be unavailable from code.

I read the same Binding a Java Library article you did, went through the instructions, and had no build errors. When I attempted to use the classes from my jar file, intellisense was not recognizing anything. Then I read the follow-on article on API Metadata Reference. This got me thinking that perhaps I should try editing the Transforms/Metadata.xml file. After editing that briefly to include a rename of the package, Visual studio allowed (after a compile) a reference to a class from the jar file. I then attempted to call a method from the class, and again, got another compiler error. So, I went back into the Metadata.xml file and added an entry to rename the method in question. I edited my code to call the renamed method, and Visual Studio compiled fine. I integrated this call into a unit test case, and it passed!
From my reading, it didn't seem necessary to edit the Metadata.xml file, but at least in my experience it seemed necessary. It uses XPATH on the obj/Release/api.xml file (as stated in API Metadata Reference). From that article there were examples for renaming both package & method names, so it wasn't much work for me to insert into my Metadata.xml file. In addition, I downloaded the OsmBindingDroidExample from the Binding a Java Library article and checked out their Metadata.xml file as well.
Here's my XML for reference as well:
<metadata>
<attr path="/api/package[#name='com.abc.def']" name="managedName">MyRenamedPackage</attr>
<attr path="/api/package[#name='com.abc.def']/class[#name='MyClass']/method[#name='originalJavaMethod']" name="managedName">RenamedDotNetMethod</attr>
</metadata>
So, now in my .NET code, I could write:
MyRenamedPackage.MyClass.RenamedDotNetMethod(...);
Hope this helps!
EDIT:
I've gotten a bit more familiar with the Xamarin toolkit, and have an update to make using this easier.
In order to limit the involvement of code that needs to interact with the jar methods, Xamarin allows you to create C# classes in the Additions folder. So, I created a wrapper class that exposes the methods in a managed C# class that other projects can access. Since it's C# there's no complaints from Visual Studio.
Here's what a wrapper class would look like going with my earlier example (obviously you'd pick a name more meaningful to the task at hand):
public class InovcationWrapper
{
public static void InvokeMethod(...)
{
MyRenamedPackage.MyClass.RenamedDotNetMethod(...);
}
}
Then in your project code, you'd have full intellisense if you just call your wrapper class:
InvocationWrapper.InvokeMethod(...);
This makes it much easier to work with and limits the amount of red squiggles to be ignored in your code. Hope this helps!

How do I get an Android application to use the Google API library in Eclipse?

I am trying to use Google's URL Shortening service in my Android app. I have imported the necessary jar files as mentioned here
I am following this as my reference to code from.
I am able to import the HTTPTransport class from com.google.api.client.http, but I am not able to import the GoogleTransport, GoogleHeaders, JsonHttpParser, nor Result, and JsonHttpContent doesn't seem to have the no-arg constructor given in the example I'm looking at.
Below is a screenshot of my project properties window, on the Libraries tab.

Copy all your jar files in your project libs folder. And remove these jars from Build Path Libraries as showing in image.

It turns out that you can use the Google Plugin for Eclipse to add an API to an Android project, as detailed here. Unfortunately, I still have the problem that I can't use the classes in any example I have found thus far. I guess I must just be using the library wrong.

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.