java - Evaluating a math expression given in string form -


i'm trying write java routine evaluate simple math expressions string values like:

  1. "5+3"
  2. "10-40"
  3. "10*3"

i want avoid lot of if-then-else statements. how can this?

with jdk1.6, can use built-in javascript engine.

import javax.script.scriptenginemanager; import javax.script.scriptengine; import javax.script.scriptexception;  public class test {   public static void main(string[] args) throws scriptexception {     scriptenginemanager mgr = new scriptenginemanager();     scriptengine engine = mgr.getenginebyname("javascript");     string foo = "40+2";     system.out.println(engine.eval(foo));     }  }

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