java - 如果找不到文件尝试结束程序

Question

如果 if 语句返回文件不存在，我将尝试终止程序。目前的方法是

public static void calcMarks() 
  {
      String Assessment1 = null, Assessment2 = null, Assessment3 = null;
      int mark1 = 0,mark2 = 0,mark3 = 0,sum = 0;
       try {
       File doc = new File ("marks.txt");
       if(!doc.exists())
       {
        System.out.println ("Marks.txt Does Not Exist");
        System.exit(); 
       }
       if(!marks.exists())
       {
         System.out.println ("TotalMarks.txt Does Not Exist");
         System.exit(); 
       }
       Scanner input = new Scanner(doc);
         while (input.hasNext()){
          Assessment1 = input.next();
          mark1 = input.nextInt();
          Assessment2 = input.next();
          mark2 = input.nextInt();
          Assessment3 = input.next();
          mark3 = input.nextInt();

        }  
      input.close();
      sum = mark1 + mark2 + mark3;
      System.out.println(Assessment1 + " "  +mark1  +"\n"+  Assessment2  + " "+mark2 +"\n"+  Assessment3  + " "+mark3+ "\n" + "Total" +""+ "=" + sum);
    }
    catch (FileNotFoundException ex) {
      System.err.println("File has not been found");
    } 

     }

但在 System.exit() 上；是 if 语句，我在 Jaba.lang.system 中收到错误 exit(int) 。不能应用于 ()

我不知道这意味着什么

Answer 1

您需要在 exit() 方法中传递返回值。最佳情况下，您应该有 System.exit( 0 );。

您可以阅读this .