This is a fork of the ZCash Swing Wallet from vaklinov. You can find the original here
https://github.com/vaklinov/zcash-swing-wallet-ui
It has since diverged greatly from upstream and is unlikely to be merged, although new features added to the original may be ported on a case-by-case basis.
This fork is not really intended for standalone use. radix42 maintains a complete OS X/Mac OS installation package here:
https://github.com/radix42/zcash4mac
Usually what happens is I write the Java bits of the wallet and push here, then radix42 pulls into his repo and builds the Mac installer.
If you insist on building this standalone, follow the instructions from vaklinov except you'll need JDK 8.