Since Android is based off of Java you have to download the JDK in order to compile and run your code!
Android Studios is the default Android IDE, make sure to download it and the SDKs when you fully install Android Studios. SDKs are Kits for specific information on android versions in order to compile your code.
Genymotion is usually a better way to test your Android apps on your computer as the native emulators that Android Studios provide.
For PC & Mac: Download Genymotion
Also for Mac: Download Virtualbox