This may be due to using a machine with a higher resolution display (such as a Surface Book) and Java not scaling the app correctly. To fix this, you can override the high-dpi settings by doing the following:
1. Find the file C:\Program Files\Java\jre1.8.0_131\bin\jp2launcher.exe
2. Right click on it, and go to Properties
3. Click on the compatibility tab
4. Check the box "Override high dpi scaling behavior"
5. Set "scaling performed by" to "system"