You need to create new layout files for tablet versions, Java part is enough but layouts and image drawables are the main things you need.
Go through Supporting Multiple Screens, Here you will have a complete idea about how to create UI supporting Tablets and their res folders.
For all tablet resolutions check this link
below are the available resolutions for android mobile and tablet
1 2560*1600
2 1366*768
3 1280*800
4 1280*768
5 1024*768
6 1024*600
7 960*640
8 960*540
9 854*480
10 800*600
11 800*480
12 800*400
13 640*360
14 640*240
15 480*320
16 400*240
17 320*240
Most Common tablet resolutions are
Samsung Galaxy Tab 10.1 3G - 10.1 inches, 1280 x 800 pixels
Samsung P1000 Galaxy Tab - 7.0 inches, 600 x 1024 pixels