Error while using '*' as command line argument

Question

class Expr
public static void main(String[] args)
     if(args.length!=3)
          System.out.println("Usage: java Expr val1 opr val2");
          System.exit(0);
     int a = Integer.parseInt(args[0]);
     char opr=args[1].charAt(0);
     int b = Integer.parseInt(args[2]);
     switch(opr)
          case '+': System.out.println(a+b); break;
          case '-': System.out.println(a-b); break;
          case '*': System.out.println(a*b); break;
          case '/': System.out.println(a/b); break;
          default: System.out.println("Invalid operator");
Abouve program compiled well
At execution if i say
java Expr 10 + 20 its working fine and give me 30 as output
But if i say
java Expr 10 * 20 [its not taking them as three arguments]
if i say
java Expr 10 "*" 20 [its working]
Please explain me why
thankas and regards
madhu.apps

Answer 1

That is more an OS question, than a Java question. But, it's because * has meaning to the shell whereas the other symbols (at least at that point) do not.