Java - 從文件中讀取有符號整數

Question

我試圖從一個文件中讀取10個有符號整數到一個數組，由於某種原因，它沒有發生，我沒有在編譯和運行時得到任何錯誤。 我只是想要第二雙眼睛看看這個，看看我可能會缺少什么。

測試文件是“input.txt”並包含：-1,4,32,0，-12,2,30,1，-3，-32

這是我的代碼：

  public void readFromFile(String filename)
  {
     try {
        File f = new File(filename);
        Scanner scan  = new Scanner(f);
        String nextLine;
        int[] testAry = new int[10];
        int i = 0;

        while (scan.hasNextInt())
        {
           testAry[i] = scan.nextInt();
           i++;
        }
     }
        catch (FileNotFoundException fnf)
        {
           System.out.println(fnf.getMessage());
        }
  } 

Answer 1

您使用Scanner對象上的默認分隔符。

嘗試使用我在行中使用的分隔符useDelimiter（\\\\ s *，\\\\ s *“）。它的正則表達式用逗號分隔文件中的輸入。

 try {
            File f = new File("input.txt");
            Scanner scan = new Scanner(f);
            scan.useDelimiter("\\s*,\\s*");
            String nextLine; //left it in even tho you are not using it
            int[] testAry = new int[10];
            int i = 0;

            while (scan.hasNextInt()) {
                testAry[i] = scan.nextInt();
                System.out.println(testAry[i]);
                i++;
            }
        } catch (FileNotFoundException fnf) {
            System.out.println(fnf.getMessage());
        }

Answer 2

你可能會拋出另一個你沒有捕獲的異常

http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Scanner.html#nextInt (）

從輸入掃描的int拋出：

InputMismatchException - if the next token does not match the Integer regular expression, or is out of range
NoSuchElementException - if input is exhausted
IllegalStateException - if this scanner is closed

或者你可以去舊學校並使用緩沖讀卡器來驗證你是否正在獲取數據

try{

  FileInputStream fstream = new FileInputStream(filename);

  DataInputStream in = new DataInputStream(fstream);
  BufferedReader br = new BufferedReader(new InputStreamReader(in));
  String strLine;

  while ((strLine = br.readLine()) != null)   {

    System.out.println (strLine);
  }
  in.close();
  }catch (Exception e){
    System.err.println("Error: " + e.getMessage());
   }