如何在 while 循環中只打印一次語句？

Question

  {
  System.out.println("Enter input file name:");
  Scanner keyboard = new Scanner(System.in);
  String fileName = keyboard.nextLine();
  File read = new File(fileName);
  Scanner inputFile = new Scanner(read);

  if(read.length() == 0)
  {
     System.out.println("empty file");
     return;
  }

  inputFile.useDelimiter(":");
  String name, code, line, distance;
  System.out.println("Enter station name");
  String stationName = keyboard.nextLine();


  while(inputFile.hasNextLine())
  {
    name = inputFile.next();
    code = inputFile.next();
    line = inputFile.next();
    distance = inputFile.nextLine();

     if(stationName.equalsIgnoreCase(name))
     {
        System.out.println("Station code: " + code + " name: " + name);
        System.out.println("distance " + distance + " kms, is on the " + line + " line");
     }

     else if(!stationName.equalsIgnoreCase(name))
     {
        System.out.println("No information was found for station " + stationName);
     }

如您所見，無論文本文件中有多少行代碼，最后一行代碼都會被多次打印出來。 有沒有辦法讓這個只打印一次？ 提前致謝。

Answer 1

我想您想要做的是僅在您閱讀整個文件后才顯示此錯誤消息。 您可以使用初始化為false的布爾變量stationFound ，並在找到匹配站時將其設置為true 。 在while 循環之后，您可以檢查stationFound是否為真，如果不為真，則顯示您的錯誤消息。

請注意，您還可以在找到匹配站后使用break ，以避免在不需要時讀取整個文件。

這是它在代碼中的樣子：

boolean stationFound = false;
while(inputFile.hasNextLine())
{
    // ...
    if(stationName.equalsIgnoreCase(name))
    {
        System.out.println("Station code: " + code + " name: " + name);
        System.out.println("distance " + distance + " kms, is on the " + line + " line");
        stationFound = true;
        break;
     }
}


if(!stationFound)
{
    System.out.println("No information was found for station " + stationName);
}

Answer 2

如果你想打印一次這個語句並退出循環，你可以添加 break; 在 if 語句之后

else if(!stationName.equalsIgnoreCase(name))
     {
        System.out.println("No information was found for station " + stationName);
break;
     }

Answer 3

你有沒有考慮插入休息？

 else if(!stationName.equalsIgnoreCase(name))
{
    System.out.println("No information was found for station " + stationName);
    break;
}