请教一下
package calc;

public class Server {

public static double Getresult(double numberA,double numberB,String mark){

double result=0d;

switch (mark){
case "+ ": result=numberA+numberB;break;
case "- ": result=numberA-numberB;break;
case "* ": result=numberA*numberB;break;
case "/ ": result=numberA/numberB;break;

}


return result;


}

}
请问一下、这个哪边有错么？

[解决办法]
public class Server {

public static double Getresult(double numberA,double numberB){

double result=0d;
char mark='+'; //最好设置个初始值，或者用System.in手动输入符号
switch(mark){
case '+': result=numberA+numberB;break;
case '-': result=numberA-numberB;break;
case '*': result=numberA*numberB;break;
case '/': result=numberA/numberB;break;

}


return result;


}
public static void main(String args[]){
double m=Getresult(3.0,4.0);
System.out.print(m);
}

}