使用輸入文件創建一個對象並將該對象添加到一個數組中，並讓它打印出該數組的信息

Question

這是我的代碼，它接收一個文本文件並創建一個Account對象，我遇到的問題是打印出銀行帳戶組中的帳戶對象

  public static void main (String[] args)
   {
      try {

          // Read data from a file into a Bank.
          // Each line of the file has info for one account.  
          BankInterface myBank = readFromFile("BankAccounts.txt");

          // Print all the data stored in the bank.
          System.out.println (myBank);

      } // end try  
      catch (IOException ioe) {
         System.out.println("IOException in main: " + ioe.getMessage()); 
         ioe.printStackTrace();
      } // end catch
      catch (Exception e) {
         System.out.println("Exception in main: " + e.getMessage());
         e.printStackTrace();
      } // end catch
   } // end main


   /**
    * readFromFile:    **** INSERT COMMENTS ****
    * 
    */
   public static BankInterface readFromFile (String fileName) throws IOException
   {
       // Creata a bank.
       BankInterface myBank = new Bank("Bank");

         // Open a file for reading.
         Scanner inputSource = new Scanner (new File(fileName));

         // while there are more tokens to read from the input source...
     while (inputSource.hasNext()) {

        // Read one line of input from the file into an Account object
            Account acct = InputManager.readOneAccountFrom (inputSource);
        // Store the account info in the bank.
        //**** INSERT CODE TO ADD acct TO THE BANK ****
        myBank.addAccount(acct);

     } // end while


         return myBank;

    } // end readFromFile

當我運行主要我沒有得到帳戶打印出來時我得到：

Reading: name,id,balance
Exception in main: null

有人可以解釋為什么會這樣，以及如何解決它？ 堆棧跟蹤：

java.util.NoSuchElementException
    at java.util.Scanner.throwFor(Scanner.java:862)
    at java.util.Scanner.next(Scanner.java:1371)
    at InputManager.readOneAccountFrom(InputManager.java:30)
    at ATM.readFromFile(ATM.java:48)
    at ATM.main(ATM.java:15)
    at __SHELL3.run(__SHELL3.java:6)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at bluej.runtime.ExecServer$3.run(ExecServer.java:730)

這是readOneAccountFrom方法：

public static Account readOneAccountFrom (Scanner inputSource)
{
    // Read one line of account data into oneLine
    System.out.println ("Reading: name,id,balance");
    String oneLine = inputSource.nextLine();

    // Parse line of account data, separated by commas.
    Scanner lineTokenizer = new Scanner (oneLine);
    lineTokenizer.useDelimiter (",");

    // Get account data (i.e. name, accountNum and balance) from oneLine
    String name = lineTokenizer.next ();
    String accountNum = lineTokenizer.next ();
    Money balance = new Money(lineTokenizer.nextLong());

    // Create and return an Account object with the data read for one   account.
    Account oneAccount = new Account (name, accountNum, balance);
    System.out.println ("Account read: " + oneAccount);

    return oneAccount;
} // end readOneAccountFrom

Answer 1

即使你的評論說

//從文件中讀取一行輸入到Account對象

你沒有正確讀線。

您應該使用hasNextLine（）和nextLine（）從掃描程序中讀取一行。 如下所示：

while (inputSource.hasNextLine()) {
      String line = inputSource.nextLine();