JEP is a Java mathematical expression parser.
This means that you can pass JEP a string of mathematical
operations (which may also contain variables) to perform and get
back an answer.

To start using JEP, create an instance of the
parser:

JEP j = new JEP();

Then, if you plan on using functions such as sin or cos, you need to tell JEP
to expect these by calling the parser’s addStandardFunctions
method:

j.addStandardFunctions();

You’re ready to start parsing. Call the
parseExpression method with the expression that needs parsing. In
this case, we’ll parse whatever is passed from the command
line:

j.parseExpression(args[0]);

Now print the result:

System.out.println(j.getValue());

For example, if the expression was “75 * 4 / (3
* 100)”, the output would be:

1.0

If you want to use variables in your
expression, you must tell JEP to expect these variables by calling
the parser’s addVariable method:

j.addVariable(“x”, 0);

One thing to keep in mind if you decide to use
JEP in your code is that JEP comes with one of two licenses: GPL or
commercial. Depending on the environment you plan on using it in,
the license type may be important to you.

Below is a complete example that parses the
expression passed in as a command line argument.

import org.nfunk.jep.JEP;

public class JepTip {
    public static void main(String []args)
{
        JEP j = new
JEP();

        j.addStandardFunctions();

        j.parseExpression(args[0]);

        System.out.println(j.getValue());

    }
}

Visit
the JEP Web site to get complete documentation and plenty of
sample code.

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