公共靜態方法返回問題

Question

我已經創建了一個用戶添加值的text.file。這是用戶數據被讀取和驗證的部分。我的努力是，當用戶在提示時添加值時，它不會返回任何數據。它顯示爲零。我不能在某處返回值。

以下是本節的說明。

「詢問用戶是否有任何更多的金額補充，不是在文本文件Ifso： 使用靜態方法來讀取和驗證金額類型和數量 使用實例方法將金額添加到總計「

這裏是我到目前爲止。感謝任何方向和幫助。

public static char readValidateAmountType() 
{ 
    System.out.println("Enter the amount type(T, D, E) you would like to enter: "); 
    Scanner keyboard = new Scanner(System.in); 
     char amountType = keyboard.next().charAt(0); 
     amountType = Character.toUpperCase(amountType); 
      do 
      { 
       if(amountType !='T' && amountType !='D' && amountType !='E') 
       { 

        System.out.println("Invalid amount type!"); 
        System.out.println("Enter the amount type(T, D, E) you would like to enter: "); 
        amountType = keyboard.next().charAt(0); 
        amountType = Character.toUpperCase(amountType); 
       } 
       else 
       { 
        return amountType; 
       }  
      } 
      while(amountType !='T' && amountType !='D' && amountType !='E'); 
      return amountType;  
} 

public static double readValidateAmount() 
{ 
    Scanner keyboard = new Scanner(System.in); 
    System.out.println("Please enter a dollar amount: "); 
    amount = keyboard.nextDouble(); 
    if(amount <=0) 
    { 
     do 
     {  
      System.out.println("Invalid amount!"); 
      System.out.println("Please enter a dollar amount: "); 
      amount = keyboard.nextDouble(); 
     } 
     while(amount <=0); 
     return amount; 
    } 
    else 
    { 
     return amount; 
    } 

主要：

public static void main (String[] args) throws IOException 
{ 
    HenwoodEventClass event = new HenwoodEventClass(); 
    System.out.println("This program will tell you the financial details of" 
      + " your event. \nAnd allow you to change or add input.\n\n"); 

    String userFile = "Event.txt"; 
    try 
    { 
     File inputFile = new File (userFile); 

     Scanner CheckFile = new Scanner (inputFile); 

     if(CheckFile.hasNextLine()) 
     { 
      while (CheckFile.hasNextLine()) 
      { 
       try 
       { 
        System.out.println(CheckFile.nextLine());  
       } 
       catch (IllegalArgumentException exception) 
       { 
        System.out.println("Does not exist!"); 
       } 
      } 
      CheckFile.close();  
      event.gettotalTicketSales(); 
      event.gettotalMoneyDonated(); 
      event.gettotalExpenses(); 
     } 
      System.out.println("Are ther anymore amounts to add that were not in the textfile?: "); 
      Scanner keyboard = new Scanner(System.in); 
      char choice = keyboard.next().charAt(0); 
      choice = Character.toUpperCase(choice); 

       do 
       { 
        if(choice == 'Y') 
        { 
         readValidateAmountType(); 
         readValidateAmount(); 

         System.out.println("Are ther anymore amounts to add that were not in the textfile?: "); 
         choice = keyboard.next().charAt(0); 
         choice = Character.toUpperCase(choice); 
        } 
        event.displayFinalResults(); 
       } 
       while(choice =='Y');   
    } 
    catch (FileNotFoundException exception) 
    { 
     System.out.println("File "+ userFile +" does not exist!\n\n"); 
    } 
} 

}

Answer 1

嘗試Double.parseDouble(keyboard.nextLine());代替nextDouble()與nextLine()取代next()。

參見：By default, a scanner uses white space to separate tokens.