Tool Required to learn Android Development :-

The Eclipse IDE.

The Android SDK.

The Android Development Tools(ADT) Eclipse plugin

System Requirements

The sections below describe the system and software requirements for developing Android applications using the Android SDK.

Windows XP (32-bit), Vista (32- or 64-bit), or Windows 7 (32- or 64-bit)
Mac OS X 10.5.8 or later (x86 only)
Linux (tested on Ubuntu Linux, Lucid Lynx)
GNU C Library (glibc) 2.7 or later is required
On Ubuntu Linux, version 8.04 or later is required
64-bit distributions must be capable of running 32-bit applications. For information about how to add support for 32-bit applications.