Error with Equation parsing (java) -
i have code:
public class parse { static double eval(string exp) { scriptenginemanager mgr = new scriptenginemanager(); scriptengine engine = mgr.getenginebyname("javascript"); string stringresult = null; try { arraylist<variable> vars = askforvars(parse1(exp)); arraylist<string> usednames = new arraylist<string>(); (variable v : vars) { if (!usednames.contains(v.name)) { stringresult = replacestring(exp, v.name, "" + v.valueused); usednames.add(v.name); } return double.parsedouble(engine.eval(stringresult.tostring()) .tostring()); } } catch (exception ex) { ex.printstacktrace(); } return 0.0; } static arraylist<variable> parse1(string exp) { arraylist<variable> variables = new arraylist<variable>(); scriptenginemanager mgr = new scriptenginemanager(); scriptengine engine = mgr.getenginebyname("javascript"); string stringresult; try { stringresult = exp; (character c : stringresult.tochararray()) { if (c.isletter(c)) { variables.add(new variable(c.tostring(), 1.0)); } } } catch (exception ex) { ex.printstacktrace(); } return variables; } static arraylist<variable> askforvars(arraylist<variable> as) { arraylist<variable> result = new arraylist<variable>(); arraylist<string> usednames = new arraylist<string>(); (variable v : as) { if (!usednames.contains(v.name)) { system.out.print("value of " + v.name + ": "); double input = double.parsedouble(messageutil.getinput()); result.add(new variable(v.name, input)); usednames.add(v.name); } } return result; } static string replacestring(string s, string from, string to) { return s.replaceall(from, to); } } it ok when have 1 variable (eg: 2x, 3x+2x or on) problem comes when use more 1 (eg: x+y, 3x-3y, or on).
this error:
value of x: 3 value of y: 4 javax.script.scriptexception: sun.org.mozilla.javascript.internal.ecmaerror: referenceerror: "y" not defined. (#1) in @ line number 1 @ com.sun.script.javascript.rhinoscriptengine.eval(rhinoscriptengine.java:156) @ com.sun.script.javascript.rhinoscriptengine.eval(rhinoscriptengine.java:170) @ javax.script.abstractscriptengine.eval(abstractscriptengine.java:247) @ com.company.parse.eval(parse.java:24) @ com.company.messageutil.createexp(messageutil.java:97) @ com.company.main.main(main.java:28) x+y resolves to: 0.0