Tutorial

Table of contents:

• Using Built-in evaluator
  • The simplest way
  • Working with variables
• Customizing Built-in evaluator
  • Restricting an evaluator
  • Extending an evaluator
  • Localizing an evaluator
• Creating your own evaluators
  • Creating a simple evaluator from scratch
  • Creating a complex evaluator
  • Working with textual operators

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Using built-in evaluator

The simplest way

Javaluator comes with a built-in expression parser that is able to parse expression on real numbers.
You simply need to instanciate it (call DoubleEvaluator default constructor) and use it (call the evaluate method).

Here is a sample code:

package com.fathzer.soft.javaluator.examples;
 
import com.fathzer.soft.javaluator.DoubleEvaluator;
 
/** The most simple class to use the built-in real expression evaluator.*/
public class Simplest {
  public static void main(String[] args) {
    // Create a new evaluator
    DoubleEvaluator evaluator = new DoubleEvaluator();
    String expression = "(2^3-1)*sin(pi/4)/ln(pi^2)";
    // Evaluate an expression
    Double result = evaluator.evaluate(expression);
    // Ouput the result
    System.out.println(expression + " = " + result);
  }
}

The output is (2^3-1)*sin(pi/4)/ln(pi^2) = 2.1619718020347976