How Can Java Efficiently Parse and Evaluate Mathematical Expressions Given as Strings?

Parsing Mathematical Expressions as Strings in Java

Given a mathematical expression represented as a string, such as "5 4*(7-15)", is it possible to evaluate and return the numeric result in Java? Additionally, what methods offer the most efficient parsing of arithmetic expressions?

Solution:

One approach to evaluating mathematical expressions as strings is to leverage the BeanShell bsh.Interpreter class. The following code demonstrates this technique:

Interpreter interpreter = new Interpreter();
interpreter.eval("result = 5+4*(7-15)");
System.out.println(interpreter.get("result"));

This approach safeguards against potential security risks by ensuring that the string to be evaluated originates from a reliable source.

Alternatively, a more complex yet secure option is to employ ANTLR (ANother Tool for Language Recognition). ANTLR constitutes a grammar-based parser generator, capable of handling mathematical expressions as a starting point.

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