java将字符串转换为算术运算

需求：将字符串“9-1+8-2+7-3+6-4+5-5”转换成算术运算，得出结果20，并返回

解决办法：

 ScriptEngineManager manager = new ScriptEngineManager(); //javax.script.ScriptEngine;
  ScriptEngine engine = manager.getEngineByName("javascript"); 
  

  String s = "5+8-2*3-2/2+7";// 13
  Object d =  engine.eval(s);

  System.out.print(d);//13.0