Antlr v4 parses a text string as a simple arithmetic expression.

com.rogersalumni.calculator.CalculatorAppImpl takes a valid arithmetic expression from the command line, returning its evaluated result - or a parsing error, depeding upon what it encounters.

If no expression supplied, it assumes the following input "-1 / 2".

Example 1:

13:58:25.680 [main] INFO com.rogersalumni.calculator.CalculatorAppImpl: (5-4)*(12-11)/((((5-4)*(12-11)))) = 1.0

Example 2:

13:59:54.817 [main] INFO com.rogersalumni.calculator.CalculatorAppImpl: 2+4+-4+-2*10%9*7 = -12.0

Example 3:

14:00:57.800 [main] INFO com.rogersalumni.calculator.CalculatorAppImpl: -2+2*10+2 = 20.0

For complete information: https://keyholesoftware.com/2020/01/21/an-antlr4-based-expression-parser/