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Compile errors in new Android project in Eclipse

I'm using Eclipse for build an Android project. when I try to open bellow item :
file --> new --> Android Application Project
Then when the project is built a series errors displayed :
I am a beginner in this regard and thank you for your help.

Open AppCompactv7 and add as library on your project

The problem is with your appcompat_v7 project. Delete the existing project one in the workspace and re-import it from
\sdk\extras\android\support\v7\appcompat
After that try cleaning the project.
Project -> select Clean -> select the project.

1 - Make sure library project(appcompat_v7) is open & is proper referenced (added as library) in your application project.To do this follow this steps: right click in your project -> "Properties - Android - Add"
2 - Delete android-support-v4.jar from your project's libs folder(if jar is present).
3 - Appcompat_v7 must have android-support-v4.jar & android-support-v7-appcompat.jar inside it's libs folder. (If jars are not present copy them from /sdk/extras/android/support/v7/appcompat/libs folder of your installed android sdk location)
4- Check whether ActionBarActivity is properly imported. (In your case this is right)
import android.support.v7.app.ActionBarActivity;
Here is a good example of how to create a project in Eclipse using v7 Support Library
Finally because you are a beginner I'll recommend you to use Android Studio as it is the official environment for developing for Android. Configuring the SDK can be quite a pain in Eclipse. You can also take advantage of the Gradle dependency system and simply specify which libraries you would like to use and Android Studio will automatically fetch the jars from online remotes as required. I think its the future of Android Application Development.

Building a project on Eclipse didn't output any bin/*.jar file

downloaded the following open source.
https://github.com/umano/AndroidSlidingUpPanel
Import /library to Eclipse as a Existing Android Code.
There's no error after building the project.
I would like to add the library to my developing app. So I guess I have to build it successfully with library.jar being output to /bin. Or is there other way to make dependency between them ?

You should set the AndroidSlidingUpPanel project as library project. After doing that, in eclipse, right click on your project in which you want to add the AndroidSlidingUpPanel project and go to properties. Then go to android section. In the bottom, click on add Library and select the project. You don't need to add jar manually, eclipse will do that for you.

Project library not getting added to android project

Iam trying to reference a Android project library to my application. I do this:-
1)File->Import->General->Existing project into workspace->Select project library->check copy to workspace.
2)Right click on project->Properties->Android-> Add-> Select project library-> Apply-> ok.
But when I again check if the library is added I get the following:-
How do I resolve this?

Make sure that your library has the same location with your project source files.
It means that if your source is on your workspace , then your library should add into workspace. If not, you should copy your lib into same folder with source then mount it again.

Make sure the library project is checked as a library.
Go to the library projects BuildConfig -> Android -> Check "is library"
Make sure your project and the library project have the same target/min SDK versions.
It's also a good idea to clean your workspace and Build the library project - Right click on library project -> "Build Project"

Try this answer:
The project name needs match the folder name on the file system. What you are seeing in the Project Properties->Android->Library Reference is a relative file system path.
Reference:
In eclipse, unable to reference an android library project in another android project
Thanks to archie-bpgc for comment

i am also facing this problem i have solve this problem like
when import lib in to workspace tick mark as show in picture (basically library project and your project both are in same workspace)
now add lib to your project and clean project

you need to import the project to workspace and the library file into the same workspace.
Then you will not face this error. Kindly the root cause is not known. But this method works.
After all this .. one more way is you can alter the project properties last line where the library file path is specified.
Thank you.

Being told project is not using the gradle build system when it is

When I open my project in Android Studio, I always get this.
Back when Android Studio first came out, I went through this process so the project should have the Gradle build system. There is a build.gradle file in the root of the project.
I can still build and run the project, but I don't understand why it always says this since the project should use gradle build system. Any help with this would be great.

The android studio support two "build mode". one is "legacy" and one is "gradle based". If you are using an very early version of android studio, probably you are still using the legacy build mode. You need to re-import your project using "gradle mode" then this warning will be gone.
To do so, select "file/import project", select your project root directory, and in the next dialog choose "Import project from external model" and select gradle. Then, you may choose "gradle wrapper" or use your own gradle distribution (1.8 for now[12/2013]).

This link can help, https://developer.android.com/studio/intro/migrate.html
Import as a Project:
Start Android Studio and close any open Android Studio projects.
From the Android Studio menu click File > New > Import Project.
Alternatively, from the Welcome screen, click Import project (Eclipse ADT, Gradle, etc.).
Select the Eclipse ADT project folder with the AndroidManifest.xml file and click Ok.

i know this is an old question but is still valid with newer versions of AS.
If you try to import and import againa and still have the same issue, check if there's a gradle.build file on the root directory, if there's not just create one.
In my case I had to migrate an old project to the new version because with the 0.4.4+ version it stopped recognizing it, and it kept failing, and that was the problem.
Curious thing is the top level build.gradle file just contains this comment:
// Top-level build file where you can add configuration options common to all sub-projects/modules.

I fixed this issue with the following steps:
Make sure that the following two files are in your project directory. If not, create a new one with reference of your other Android projects. These are default auto-generated files.
settings.gradle
build.gradle
If it is still showing any errors when you open your project, restart your project by selecting file/(invalidate /restart).

import Project
File --> New -->import Project

In my case the the problem was that studio version I am using does not support the gradle version of file, so in build.gradle I had to change the gradle version to 2.3.0 and everything is smooth now

Android Studio The project is already registered

I've a big problem with Android Studio.
I have a project that depends on two other projects (as libs).
I followed the guide Problems importing project into Android Studio regarding ActionBarSherlock for import external modules.
I opened "Project Structure", imported the module, but after that I can't see it in the Modules area.
The Modules area contains only the root module, seems it is not refreshed (this is strange). So if I try to add the module as a Dependency, Android Studio doesn't find any module!
Then, if I try to re-import the module, it says that the module/project is already registered!!
Maybe I'm missing something, but I don't know what....! I have this problem both on Windows and MacOSX.
Thanks in advance,
Federico

Look around in your .idea directory for mentions of the problematic project. I had the same problem and resolved it by deleting the entry from .idea/sbt.xml.

In ij go to menu: View -> Tool Windows-> Gradle
Right click on the problematic module and click Refresh External Project, You should see the module in project explorer.

I had a similar problem with ABS and other library imports. The 'Project Structure' interface just wouldn't show the modules. On trying to import the modules, it would prompt, "The project is already registered". Seems to be an IntelliJ/Android Studio issue. Invalidate Caches option didn't help.
Reimporting the project after some cleanup did work for me.
As a precaution, take a backup of your project and store it safely
Ensure that your project builds via gradle command-line and you have all required dependencies specified in respective build.gradle files. Try building with: gradle clean && gradle build
Close the project in Android Studio (or close Android Studio)
Delete .iml files and .idea folders from all modules and the main project
Start Android Studio and reimport the project (Import project from external model > Gradle)

you should remove the project from respective gradle/sbt/maven/ant tab (used to be on right vertical line of Android Studio/Intellij IDEA)
See this answer: https://stackoverflow.com/a/30442195/907576

My issue was fixed when I restart IDEA.