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How to import 3rd party libraries

I found some cool android libraries the other day and decided to try some. But I'm having trouble correctly importing the library.
This is the URL of the library : https://github.com/dmytrodanylyk/android-process-button
I first tried importing the library to eclipse (and move the files in java directory to src directory and set the project as library) and importing the sample to eclipse and set it to use the library project (Properties->Android->Libraries). But it didn't work. The layout files said it failed to instantiate [custom widget class].
The I tried importing the .jar file to libs directory (and update the java build path) but it didn't work either. It showed errors in the java files too.
I then tried copying all the java and layout files to the sample project directory and it worked. But I'm guessing that's not the way to work with 3rd party libraries.
I first thought it's some error with the library but all the other libraries I tried to import to my projects faced the same problem.
Can someone walk me through how to correctly import a 3rd party library to my android project?

The best option you can do is to use gradle as your dependency manager.
The library you have posted is using Gradle so you can link to this library in this way:
dependencies {
compile 'com.github.dmytrodanylyk.android-process-button:library:0.0.7'
}
And voilá! You have your library ready to use in your app :D
I'll let you a couple of useful links to use Gradle properly:
Mark Allison's tutorial about Gradle It will explain step by step how Gradle works (keep in mind that is using an outdated version of Android Gradle plugin, you have to adapt the version to the current one which is 0.10)
Official Developer Docs about Gradle In here you can find another step by step tutorial to configure and use Gradle (this one is more updated).
You can use Gradle directly in Android Studio (Intellij) if you don't mind to change your main editor.
If you want to stick around with Eclipse then this stackoverflow link may be helpful!
EDIT:
Oh! And if you want to search already Gradlized libraries you can navigate to Gradle Please!

I see the library uses gradle. So if you use gradle for dependency management or Android Studio (which uses gradle by default) importing will be a breeze. The installation instruction for gradle is even available at the github project site.
dependencies {
compile 'com.github.dmytrodanylyk.android-process-button:library:0.0.7'
}

Stuck with first time java for android

guys, with my friend started working on a school project - developing a java app for android. He started it, now it's my turn to do my job, so i got the code he already has, set up Android SDK for Eclipse and downloaded all the neccessary files and packages, but it still gives me errors and I can't even run the project.
One of the errors (the main one, I think) is that it can't import android.support.v7.app.ActionBarActivity
If anyone knows what can I do (I've tried all kinds of solutions from the internet, but none work) I would be very grateful.
Here is a screenshot of the code
http://s17.postimg.org/8aw952lha/Capture.jpg

See if you have imported the ActionBar project to your Eclipse workspace, also, right click on your project->properties->android and check that you have referenced/linked the ActionBar project there.
If you are using a repository without the proper ignore files it is possible that you have imported your partners configurations and then have the references to the auxiliary projects broken (you just need to update that).
Hope it helps.

android.support.v7.app.ActionBarActivity is a support library. This allows older versions of Android (before native support for an action bar was available) to use the action bar.
Since you are having difficulty importing it, I'd assume you do not have the support library installed.
Full instructions are available here:
http://developer.android.com/tools/support-library/setup.html
A snippet for adding support libraries to Eclipse:
Make sure you have downloaded the Android Support Library using the SDK Manager.
Create a libs/ directory in the root of your application project.
Copy the JAR file from your Android SDK installation directory (e.g., /extras/android/support/v4/android-support-v4.jar) into your application's project libs/ directory.
Right click the JAR file and select Build Path > Add to Build Path.

Java - Android - NoClassDefFoundError - "Could not find class" error in Logcat

First of all, I realise that similar questions have been posted a lot here. But I've been through all of the answers I can find to similar problems, and nothing has worked yet, so was wondering if someone could help me.
I'm trying to develop a simple chat app with an Android client and a server app sitting running on my laptop. This includes a regular Java "common" project that holds the class that is used to pass messages via the socket.
First I tried to reference the "common" project in the Android project, but after a bit of reading abandoned that idea.
Now I have exported the jar file for the common project, and imported it into my Android project by copying it into the "libs" folder, and then selecting Build Path > Add To Build Path. I have also gone to Properties > Java Build Path > Order and Export and checked the library and moved it to the top of the order.
I have also moved the "gen" project above the "src" one in that build order.
Android Private Libraries is also checked. Everything is checked.
When I debug as an Android Application to my Samsung S3, I see a "Could not find class error" in logcat when advancing to the Activity that contains a reference to a class in the "common" project. Stepping through to the point where a class in the "common" project is referenced then causes a ClassNotFoundException to be thrown.
If I try to put the name of the library in the Android Manifest, like:
<uses-library android:name="com.johndarv.chatproj.common" />
I get:
Installation error: INSTALL_FAILED_MISSING_SHARED_LIBRARY
Please check logcat output for more details.
Launch canceled!
Upon trying to install.
I have the following versions:
Eclipse Standard SDK 2.0.0
Android SDK 22.3
Android project is compiled with Android 4.2.2.
Any help would be much appreciated! If I can give any more info that would be useful, please ask!

The uses-library tag means that your app expects the library to be available on the system. This is to prevent installation on devices which do not have some expected third-party software installed. Consider phone manufacturer who ships his devices with some specific api.
So this is not your case. Forget about this tag this time.
And as to your problem. The jar is not exported into the apk.
Ensure in Project Settings > Java Build Path > Order and Export that the library jar is checked to be exported.
If you put a jar into /libs dir of android project it is automatically added to the build path. You do not need to do this manually (as you did). Then you can see it (this jar) under Android Libraries entry in under Project Settings > Java Build Path > Libraries. This entry is also checked as exported (by default in android project) in Order and Export tab.
Maybe your problm occurs due to the fact that the jar is actually exported twice (once manually and once as private library). Just remove manually added entry from build path. You will have it added once - but to be honest I do not expect this caused the problem. But for sure the problem is in your project settings. Maybe paste a screenshot with Java Build Path > Order and Export and Java Build Path > Libraries.

I managed to solve this by deleting the common project and then creating a new Java project with "Use execution environment" set to Java SE 1.6. And rewriting (copy-pasting) the old classes.
There must have been something wrong with my previous project, and looks like it was the Java version used to compile. I had tried to set the compliance version to 1.6 on the old project. In any case, creating a whole new 1.6 project, pasting the classes in, re-exporting, and copying into my Android project did the trick.
Thanks to everyone who tried to answer this for your help. Hope someone finds the above useful one day!

The import android.support cannot be resolved

I am trying to run the code provided HERE
I downloaded the code from their Github and imported into Android SDK, but it shows error at the lines
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.NavUtils;
in multiple files. However if I check the Android SDK Manager, the Android Support Library as well as the Android Support Repository in the Extras folder are both installed. I can also see the support folder and it's contents in the SDK_INSTALL\sdk\extras\android\support directory. It also has the v4 folder which also contains the android-support-v4.jar and the src folder. THen why is it still showing the error, how do I resolve it and how do I get that sample code running? THe sample code is for an RSS reader app, if that's relevant.

Follow these steps:
For Eclipse:
Go to your Project's Properties
Navigate to the Java Build Path
Then go to the Libraries tab. There click the Add External JARs Button on the Right pane.
Select the android-support-v4.jar file, usually the path for the Jar file is :
YOUR_DRIVE\android-sdks\extras\android\support\v4\android-support-v4.jar
After adding android-support-v4.jar Library, navigate to the Order and Export tab and put check mark on the android-support-v4 Library file.
After doing the above, Clean the Project and Build it.
Problem Solved.
For Android Studio:
Short Version:
Add the following line to your build.gradle file:
implementation 'com.android.support:support-v4:YOUR_TARGET_VERSION'
Long Version:
Go to File -> Project Structure
Go to "Dependencies" Tab -> Click on the Plus sign -> Go to "Library dependency"
Select the support library "support-v4 (com.android.support:support-v4:YOUR_TARGET_VERSION)"
Navigate to your "build.gradle" inside your App Directory and double check if your desired Android Support Library has been added to your dependencies.
Rebuild your project and now everything should work.
Further reading regarding this Question:
Support Library - Android Dev
Recent Support Library Revisions
Support Library Packages
What is an Android Support Library?
How do the Android Support Libraries work?

andorid-support-v4.jar is an external jar file that you have to import into your project.
This is how you do it in Android Studio:
Go to File -> Project Structure
Go to "Dependencies" Tab -> Click on the Plus sign -> Go to "Library dependency"
Select the support library "support-v4 (com.android.support:support-v4:23.0.1)"
Now to go your "build.gradle" file in your app and make sure the android support library has been added to your dependencies. Alternatively, you could've also just typed compile 'com.android.support:support-v4:23.0.1' directly into your dependencies{} instead of doing it through the GUI.
Rebuild your project and now everything should work.

Another way to solve the issue:
If you are using the support library, you need to add the appcompat lib to the project. This link shows how to add the support lib to your project.
Assuming you have added the support lib earlier but you are getting the mentioned issue, you can follow the steps below to fix that.
Right click on the project and navigate to Build Path > Configure Build Path.
On the left side of the window, select Android. You will see something like this:
You can notice that no library is referenced at the moment. Now click on the Add button shown at the bottom-right side. You will see a pop up window as shown below.
Select the appcompat lib and press OK. (Note: The lib will be shown if you have added them as mentioned earlier). Now you will see the following window:
Press OK. That's it. The lib is now added to your project (notice the red mark) and the errors relating inclusion of support lib must be gone.

For me they were appearing when i transferred code manually to another laptop. Just do
File>Invalidate Cache/Restart
click on 'Invalidate Cache and Restart' and your are done.

I followed the instructions above by Gene in Android Studio 1.5.1 but it added this to my build.gradle file:
compile 'platforms:android:android-support-v4:23.1.1'
so I changed it to:
compile 'com.android.support:support-v4:23.1.1'
And it started working.

This issue may also occur if you have multiple versions of the same support library android-support-v4.jar. If your project is using other library projects that contain different-2 versions of the support library. To resolve the issue keep the same version of support library at each place.

I have resolved it by deleting android-support-v4.jar from my Project. Because appcompat_v7 already have a copy of it.
If you have already import appcompat_v7 but still the problem doesn't solve. then try it.

This is very easy step to import any 3rd party lib or jar file into your project
Copy android-support-v4.jar file from
your_drive\android-sdks\extras\android\support\v4\android-support-v4.jar
or copy from your existing project's bin folder.
or any third party .jar file
paste copied jar file into lib folder
right click on this jar file and then click on build Path->Add to
Build Path
even still you are getting error in your project then Clean the
Project and Build it.

Android Studio 2.2.3
Linux Mint 18.1
Inside your 'project view' open Gradle Scripts -> build.gradle(Module:app) and put your mouse pointer inside the word dependencies.
Click on the light bulb and click "add library dependency" and for me all the libraries I wanted were listed there.
example libraries that came up for me:
compile 'com.android.support:gridlayout-v7:25.1.0'
compile 'com.android.support:support-v13:25.1.0'
I am now looking to add android support by default in Gradles default configuration.

How to include a Java project in an Android project?

I am using Eclipse to develop an Android board game.
I have developed the UI in an Android project.
On the other hand, I have developed the AI in a regular Java project, because I wanted to be able to test it without all the constraints of the Android emulator (I didn't find any other way to run the code using my Windows JVM).
Now comes the times when I want to 'join' both projects (which work fine independently), that is to use the AI Java classes from the UI.
This is what I have tried:
In my Android project Properties > Projects References, I ticked the Java project.
This allows me to build without error the Android project (which instantiates an AI object).
But it fails at runtime with this error:
Could not find class 'my.package.AI', referenced from method my.otherpackage.UI.onStart
What would be the correct way to include the AI Java Project into my Android Project ?
(NB: I still want to be able to develop and test the AI as a regular Java app, so I think using a jar or copying all the sources to the Android Project would not suit my needs)
EDIT:
I was hoping that the new ADT v17 would solve the problem, but it didn't. I have tried virtually every option available to include a project in my Android project:
Adding or linking a source folder
Adding a Project (Java Build Path > Projects tab)
Adding a Class Folder or a Library (Java Build Path > Library tab)
Ticking all the previously imported projets/libraries as Exported
The only way that allows compiling and running without error is adding the JAR of the Java Project to the Android project build path.

Projects References only add the dependent project source code (your AI project) as a soft (perhaps weak is a more accurate word) reference, your AI project is not added into you Android Project Build path. so the actual ai.jar is not exported into the final apk when Eclipse build your app.
You should add AI project into Android project build path:
Right-click on your android project, select Build Path - Configure Build Path, in Projects tab (Required projects on the build path), add your AI project here.
Then in Order and Export tab (Build class path order and exported entries), tick your newly added AI project appeared int the list.
Step 2 is probably optional, this should add AI project as a reference in Android project and export the ai.jar to final.apk when Eclipse build your Android project.
Update from ADT 17.0.0:
Android Dev Team just release SDK r17 with ADT 17.0.0, which claims to handle this use cases properly now:
Eclipse specific changes
The dynamic classpath container called “Library Projects” has been renamed to “Android Dependencies” as it now contains more than just Library Projects.
The container will now also be populated with Java-only projects that are referenced by Library Projects. If those Java projects also reference other Java projects and/or jar files they will be added automatically (jar files referenced through user libraries are supported as well).
Important: this only happens if the references are set to be exported in the referencing project. Note that this is not the default when adding a project or jar file to a project build path.
Library Projects (and the content of their libs/*.jar files) is always exported. This change only impacts Java-only projects and their own jar files.
Again, duplicates (both projects and jar files) are detected and removed.
More in this link.

Edit: After much testing, reading and found my solution. Problem is (as of this writing) that you can't reference another project from an Android project, although it works fine for a normal Java application project.
Workaround for me (Windows with NTFS filesystem):
In a prompt (admin rights) make a symbolic folder link using mklink /D command pointing to your source project folders, and refresh in Eclipse as needed.
The obvious limitation is you cant use the same package names in source project and target project, and then there is the problem with libs in the common project.
example:
cd \java\workspace\AndroidProject\src\your\package
mklink /D common c:\java\workspace\CommonProject\src\your\package\common
Clarification: You can reference another project from an Android project to make it compile, however when you run, the referenced classes from the included project are not put in the apk classes.dex (verified with dex decompiler).

Using ADT 21.0.0 64bit on Windows 7 64bit. I tried adding project to build path. Ticked in the Order and Export, played with order. I read the official solution, the detailed explanation of that solution, exported as JAR, added to libs. Did not work, while the source was without errors. Read in the comments that the solution didn't work for everyone.
Was fed up with it and tried a simple but somewhat messier solution: linked the Java project's source to the Android project. That did the trick. Hope that this will help others too.

Don't add it to the project references area, instead go into the Android pane (in the Project Properties), scroll down to the bottom, and add it under Libraries.
This sometimes works but sometimes produces bizarre Eclipse issues (not sure why), in which case copying the jar directly into the project seems to work best.