Install ADT (Android Developer Tools) on Eclipse

Android offers a custom plugin for the Eclipse IDE, called Android Development Tools (ADT). This plugin provides a powerful, integrated environment in which to develop Android apps. It extends the capabilities of Eclipse to let you quickly set up new Android projects, build an app UI, debug your app, and export signed (or unsigned) app packages (APKs) for distribution.

Note: Be aware that Android Studio is now the official IDE for Android, so you should migrate to Android Studio to receive all the latest IDE updates. 

You should install the ADT plugin only if you already have an Eclipse installation that you want to continue using.

~ referenec: http://developer.android.com/sdk/installing/installing-adt.html

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Download Eclipse:
It's very straightforward, visit http://www.eclipse.org/downloads/, download Eclipse IDE for Java Developers (Eclipse 3.7.2 or greater), unpack the downloaded file, and move the unpacked folder to any location you want.


Install ADT (Android Developer Tools) on Eclipse:

1. Start Eclipse, then select Help > Install New Software.
2. Click Add, in the top-right corner.
3. In the Add Repository dialog that appears, enter "ADT Plugin" for the Name and the following URL for the Location:

   https://dl-ssl.google.com/android/eclipse/

   Note: The Android Developer Tools update site requires a secure connection. Make sure the update site URL you enter starts with HTTPS.
4. Click OK.
5. In the Available Software dialog, select the checkbox next to Developer Tools and click Next.
6. In the next window, you'll see a list of the tools to be downloaded. Click Next.
7. Read and accept the license agreements, then click Finish.
   If you get a security warning saying that the authenticity or validity of the software can't be established, click OK.
8. When the installation completes, restart Eclipse.

reference: http://developer.android.com/sdk/installing/installing-adt.html