The operator - is undefined for the argument type(s) String, int 是什么错误?
System.out.println("three"+"-"+"="+three-one); System.out.println("three"+"*"+"="+three*one); System.out.println("three"+"/"+"="+three/one); 输出的第一行报错:“The operator - is undefined for the argument type(s) String, int”是什么意思啊??