pt.tumba.cage
Class MathEvaluator

java.lang.Object
  pt.tumba.cage.MathEvaluator

public class MathEvaluator
extends java.lang.Object

A Mathematic expression evaluator. Currently, the following functions are supported:

+, -, *, /, ^, %,

cos, sin, tan, acos, asin, atan,

sqrt, sqr, log,

min, max, ceil, floor, abs, neg, rndr. When the method getValue() is called, a Double object is returned. If it returns null, an error occured while parsing the expression.

 Sample:
 MathEvaluator m = new MathEvaluator("-5-6/(-2) + sqr(15+x)");
 m.addVariable("x", 15.1d);
 System.out.println( m.getValue() );
 

Author:

Bruno Martins

Constructor Summary

MathEvaluator()
Constructor for creating an empty MathEvaluator.

MathEvaluator(java.lang.String s)
Constructor for Creating a MathEvaluator and assigning a math expression string.

Method Summary

void	addVariable(java.lang.String v, double val) Adds a variable and its value in the MathEvaluator.
void	addVariable(java.lang.String v, java.lang.Double val) Adds a variable and its value in the MathEvaluator.
java.lang.Double	getValue() Evaluates and returns the value of the expression.
java.lang.Double	getVariable(java.lang.String s) Gets the variable's value that was assigned previously.
static void	main(java.lang.String[] args) Main method, used to run the program in command line.
void	reset() Resets the evaluator.
void	setExpression(java.lang.String s) Sets the expression to evaluate.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MathEvaluator

public MathEvaluator()

Constructor for creating an empty MathEvaluator. You need to use setExpression(String s) to assign a math expression string to it.

MathEvaluator

public MathEvaluator(java.lang.String s)

Constructor for Creating a MathEvaluator and assigning a math expression string.

Parameters:

s - A String with the math expression.

Method Detail

main

public static void main(java.lang.String[] args)

Main method, used to run the program in command line. Usage: java MathEvaluator.main [your math expression].

Parameters:

args[] - The command line input, tokenized.

addVariable

public void addVariable(java.lang.String v,
                        double val)

Adds a variable and its value in the MathEvaluator.

Parameters:

v - A String with the variable name.

val - the value for the variable.

addVariable

public void addVariable(java.lang.String v,
                        java.lang.Double val)

Adds a variable and its value in the MathEvaluator.

Parameters:

v - A String with the variable name.

val - the value for the variable.

getValue

public java.lang.Double getValue()

Evaluates and returns the value of the expression.

Returns:

Double the numeric value of the expression.

getVariable

public java.lang.Double getVariable(java.lang.String s)

Gets the variable's value that was assigned previously.

Parameters:

v - A String with the variable name.

Returns:

Double The value for the variable.

reset

public void reset()

Resets the evaluator.

setExpression

public void setExpression(java.lang.String s)

Sets the expression to evaluate.

Parameters:

s - A String with the expression to evaluate.