Compilation/Run commands:

(1) javac *.java
(2) java jCAS

Usage

From here, the GUI allows for input either via keyboard or the barebones buttons. There are two functions which can be called: simplify OR solve. Then, just hit '='

simplify(<expr>)
solve(<equation>)

Examples:

simplify((x+1)*2)
OR
solve(x^2=1)