調用主闖闖拋出異常

Question

後，我想拋出一個異常，這是我的代碼

System.out.println("please enter an intger to compute its factorial:"); 
    BufferedReader bufferedreader = new BufferedReader(new InputStreamReader(System.in)); 
    String number =""; 
    try { 
     try { 
      number = bufferedreader.readLine(); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 

     } 

    intN=Integer.parseInt(number); 
     if (intN > 0) {   // from the command line 
      FactorialIter f = 
       new FactorialIter(Math.abs(intN)); 

     } 
    } catch (NumberFormatException e) { 
     // TODO Auto-generated catch block 
     System.out.println("error you should enter a number"); 
     throw new MyExceptions("try again please use integer numbers"); 
     //if possible to restart the main 

    } 

所以當以往用戶輸入一個字符，程序將拋出一個異常，然後重新啓動後重新啓動程序這可能嗎？？

Answer 1

通常，不應該遞歸調用main，特別是爲了重新啓動程序。

如果您想回到程序中的某個位置，請使用循環。這裏是你如何能做到這一個例子：

boolean done = false; 
do { 
    done = true; 
    try { 
     ... 
    } catch (NumberFormatException e) { 
     System.out.println("error you should enter a number"); 
     done = false; 
    } 
} while (!done); 

循環將每個異常處理程序設置done到false時間繼續從頭開始。

Answer 2

你可以把它放在一個循環中。

While(isValid != TRUE) 
{ 
     try 
     { 
      try { 
       number = bufferedreader.readLine(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

      intN=Integer.parseInt(number); 
      if (intN > 0) {   // from the command line 
        FactorialIter f = 
         new FactorialIter(Math.abs(intN)); 
       isValid = TRUE; 

      } 

     } 
     catch (NumberFormatException e) 
     { 
      System.out.println("error you should enter a number"); 
      System.out.println("try again please use integer numbers"); 
      isValid = FALSE; 
     } 

}