java中2个或多个数字变量直接相乘相加减运算

利用Double.valueOf(str)将str转为double 类型，2个数即可直接相乘、相加减运算

String a="24.3";

String b="3";

double addResult=Double.valueOf(a)+Double.valueOf(b);

double jianResult=Double.valueOf(a)-Double.valueOf(b);

double mutiResult=Double.valueOf(a)*Double.valueOf(b);

BigDecimal c=new BigDecimal(mutiResult);