运行客户端程序就是args.length == 0
哪里出错了？
```public class ClientMain {
public static void main(String[] args) throws IOException {
if (args.length == 0){
System.out.println("You did not specify the method of performing the calculations: net or local");
return;
}
IProxy proxy;
String option = args[0];
if (option.equals("net"))
proxy = new NetProxy();
else if (option.equals("local"))
proxy = new CalculatorProxy();
else {
System.out.println("unknown input parameter: " + option);
return;
}
Scanner scanner = new Scanner(System.in);
System.out.print("Enter x: ");
double x = scanner.nextDouble();
System.out.print("Enter y: ");
double y = scanner.nextDouble();
double result = proxy.multiply(x, y);
System.out.println("Multiplication result: " + result);
}
}
