From MeasureJ2X
Mac OS X
MeasureJ2X requires Java to be installed to run. For Mac OS X up to OS X 10.9, Apple's Java 6 was integrally installed as part of the OS X installation.
Mac OS X Maverick (10.9)
Installing or updating to Mac OS X Maverick (10.9) may remove Java from your system. If it has been removed, download and install Apple's Java release [1] before installing MeasureJ2X.
Mac OS X Yosemite (10.10) or later
Java needs to be manually installed. Install either the latest version of Java from Oracle [2] or Apple's Legacy Java 6 [3]
