Cannot create jar file from sopc2DTS.java file

I was using Intel FPGA Embedded Command Shell and following instructions in this link: Sopc2dts - Intel Community to create a dts file from sopc file. However, I got stuck in the step make jar file from java file. The error is /usr/bin/sh: jar: command not found, but I dont know how to install the jar command. Please give me an instruction to overcome this problem. Thanks.