Long.parseLong(String s) 其中s必须是数字形式的字符串，才能运用该函数转化为长整型。

 public class ConverTo 

     { public static void main(String [] args)
        { String numberIn =args[0];
          convertNum(numberIn);
         }
         static void convertNum(String num)
            {
               long showNumber;
               String temp;
                 switch(num)
                { case "one":
                   temp = "1";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "two":
                   temp = "2";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "three":
                   temp ="3";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "four":
                   temp = "4";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "five":
                   temp = "5";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "six":
                   temp = "6";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "seven":
                    temp = "7";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "eight":
                    temp = "8";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "nine":
                    temp = "9";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;
                  case "ten":
                    temp = "10";
                   showNumber = Long.parseLong(temp);
                   System.out.println(num+"convert to"+showNumber);
                   break;

                  }

             }

      }

Long.parseLong(String s) 其中s必须是数字形式的字符串，才能运用该函数转化为长整型。