How to evaluate a simple Java expression in string?

Question

For example:
String result = eval("(10+sin(3.14))/2");

Answer 1

First way:
Evaluate JavaScript expression in Java via ScriptEngineManager
https://code.sololearn.com/cOdXAq93T7uz

Answer 2

Second way:
Evaluate expression via jrunscript
https://code.sololearn.com/cnG5YZ2SLEAK

Answer 3

How long does it normally take to learn python?