如何在 while 循环中只打印一次语句？

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);
     }

As you can see the final line of code will be printed out multiple times for however many lines of code there are in the text file. Is there any way to make this only print once? Thanks in advance.

Answer 1

I guess what you want to do is to display this error message only once you have read the entire file. You could use a boolean variable stationFound initialized to false and that you set to true when you found a matching station. After your while loop, you can then check if stationFound is true, and if not display your error message.

Note that you can also use a break once you have found a matching station to avoid reading the whole file when not needed.

Here is what it would look like in code:

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

If you want to print this statement once and exits the loop you can add break; after the if statement

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

Answer 3

Have you considered inserting a break?

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