I am running windows 7 and have a Galaxy Tab 4 with Wifi only. I just switched from a different computer to this one, both using Android Studio. My tablet was recognized on the other computer through the ABD, but not the new computer. I have installed the Google Nexus Drivers, the samsung driver, the JDK, and the android SDK. The only thing I have not installed are the Samsung API's because I don't believe that I need them and don't think that they would help. I have switched the Media mode from MTP to PTP several times. Anybody know how to make this work? *I have search through all of the questions and answers here and I have not found a solution that works.
Installing the driver from
http://www.samsung.com/us/support/owners/product/GT-P7510MAVXAB
worked for me. Now I can use a Samsung Galaxy Tab with Android Studio. It is recognized as a running device when you open the "Choose Device" Dialog.
Also, I enabled Developer Options and USB Debugging. (@Zhuinden pointed that out.)