To start developing Apps for Android you should do the following:
- Download and install the Java SDK 64bit Version 7 for your platform which is available here
- Then you will need to download and install Android Studio which is the IDE for developing Android Apps from here. When you download the version for your operating system it will take you through the required installation and setup steps.
- To install the additional libraries if you select Configure from the Android Studio Quick Start and the SDK Manager it will look for the latest SDK packages and will automatically select those that the install guide suggests.
Once these have installed work through the Build your first App Tutorial.
The Developers training pages have many more examples which serve as good templates to start building your own Apps and these can be imported directly into Android Studio.
If you are developing in Windows you will need the Google USB drivers. These are required for Android Debug Bridge (adb) to detect your device. The installation guide for these drivers can be found in the simple app development lab notes. They can also be found online on the Android Developer Tools page.
The following is true for windows 8.1 (I’m not sure if it is the same for iOS/Linux or windows 7): For your phone to appear in Android studio, you must enable USB debugging in the developer settings of your phone. (Enabling developer mode on the phone is necessary for all OSs.) After this has been enabled go to device manager on your PC. You will notice there are two Nexus 5’s; one is recognised as a portable device the other is unknown. The unknown device needs to have the google usb driver installed. Right click on the unknown device and update the driver manually. The directory (depending on installation settings) should be similar to this:
Note the second unknown device only appears when you have USB debugging enabled under developer settings.