netbeans - method in main read string expression in java -

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this question has answer here:

i need create method in main read string expression , parse parenthesis first.

the expression is:
(3+4)*7/2

it has done in java. don't know how it.

any ideas on that!

try this:

scriptenginemanager mgr = new scriptenginemanager(); scriptengine engine = mgr.getenginebyname("javascript"); string foo = "(3+4)*7/2"; double result=0; try {     /*     seems (on platforms) results in java.lang.runtimeexception      because of converting object double, let's replace     double.doublevalue()     */     //result = (double) (engine.eval(foo));     result = ((double) (engine.eval(foo))).doublevalue(); //result = 24.5 } catch (scriptexception e) {     //handle exception here }

update

before try evaluate expression, should test if "javascript" scriptengine registered on system, can this:

scriptenginemanager manager = new scriptenginemanager(); list<scriptenginefactory> factories = manager.getenginefactories(); (scriptenginefactory factory : factories) {     system.out.println(factory.getnames()); }

my output is

[js, rhino, javascript, javascript, ecmascript, ecmascript]

if output doesn't contain javascript, try js , javascript, like

scriptengine engine = mgr.getenginebyname("js");

or

scriptengine engine = mgr.getenginebyname("javascript");

if neither of them exist can't use js script engine evaluate expression


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