Java Scanner class reads one line and then stops

Question

I have this problem with a method using the Scanner class. I am reading my text file with Scanner and then parse the int into an array.

public static void readItems() 
{
    try 
    {
        File file = new File(System.getProperty("user.home") + "./SsGame/item.dat");
        Scanner scanner = new Scanner(file);
        int line = 0;
        while (scanner.hasNextLine())
        {
            String text = scanner.nextLine();
            text = text.replaceAll("\\W", "");
            System.out.println(text.trim());
            PlayerInstance.playerItems[line] = Integer.parseInt(text);
            line++;
        }
        scanner.close();
    } catch (FileNotFoundException e) 
    {
        e.printStackTrace();
    } catch (NumberFormatException e2)
    {
        e2.printStackTrace();
    }
}

Heres the item.txt file:

1
1
2
3
4

I run the code and I get the following output:

1

I have tried using scanner.hasNextInt() and scaner.nextInt(); for this but then it won't print anything at all.

If I remove the parseInt part then the file will finish reading and all the numbers will be printed. Any ideas?

This the exception thrown:

java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at game.player.ReadPlayer.readItems(ReadPlayer.java:56)
at game.player.ReadPlayer.read(ReadPlayer.java:11)
at game.Frame.<init>(Frame.java:32)
at game.Frame.main(Frame.java:54)

Answer 1

You need to be careful when you use the Scanner.

If you are reading more data, with Scaner like input.nextInt(); then it will read only one int. The carriage return isn't consumed by nextInt. One solution is that add input.nextLine(); so that it moves to the next line.

Other Solution is, which I prefer is to use BufferedReader;

    BufferedReader bufferRead = new BufferedReader(new InputStreamReader(System.in));
    String tempStr = bufferRead.readLine();

    // Do some operation on tempStr

Hope this helps.

Answer 2

I'm guessing Integer.ParseInt() is throwing an NumberFormatException because your line still contains the \n.

If you call Integer.ParseInt(text.trim()) instead, it may fix it.

If you did your Exception handling properly, we would have a better idea.

Answer 3

This is because, you have a NumberFormatException, while parsing integer.

Add in catch section something like this

System.out.println(e.getCause());

And see, that you have an exception, that's why this code prints only first digit.