使用scanner，java.util.InputMismatchException从文件读取double

Question

Hi guys, I'm Java's beginner and I was trying to read some data from a file but an error occurred when It tried to read the double's value and I can't figure out why. This is my code:

package bestcombo;
import java.io.*;
import java.util.Scanner;
public class Componentes 
{
    String name = "";
    Lojas[] stores = new Lojas[8];
    public void ComponenteNome(String nome)
    {
        name = nome;
    }
    public void InicializeStores()
    {
        for (int i = 0; i < 8; i++) 
        {
            stores[i] = new Lojas();
        }
    }
    public void InserirInformacao() throws IOException
    {
        int i = 0, val = 0, quant = 0;
        double price = 0;
        String FileName = "";
        Scanner ReadKeyboard = new Scanner(System.in), ReadFile = null;
        InicializeStores();
        System.out.println("File:\n");
        FileName = ReadKeyboard.nextLine();
        ReadFile = new Scanner(new File(FileName));
        while(ReadFile.hasNext())
        {
            ReadFile.useDelimiter(":");
            val = ReadFile.nextInt();
            ReadFile.useDelimiter(":");
            price = ReadFile.nextDouble();
            ReadFile.useDelimiter("\\n");
            quant = ReadFile.nextInt();
            stores[i].LojaValor(val);
            stores[i].LojaQuantidade(quant);
            stores[i].LojaPreco(price);
        }
    }
}

This is the data inside my file:

1:206.90:1
2:209.90:1
3:212.90:1
4:212.90:1
5:213.90:1
6:224.90:1
7:229.24:1
8:219.00:1

And this are the errors

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:864)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextDouble(Scanner.java:2413)
at bestcombo.Componentes.InserirInformacao(Componentes.java:34)
at bestcombo.BestCombo.main(BestCombo.java:13)

Answer 1

When reading from file I would recommend using getNextLine(), it makes for much simpler code and extraction of values. Plus your data file you read in is colon separated which makes for extraction of values quite easy. try using this while loop instead

while(ReadFile.hasNextLine())
{
    String inputOfFile = ReadFile.nextLine();
    String[] info = inputOfFile.split(":");
    try{
        if(info.length == 3)
        {
            val = Integer.parseInt(info[0]);
            price = Double.parseDouble(info[1]);
            quant = Integer.parseInt(info[2]);
            stores[i].LojaValor(val);
            stores[i].LojaQuantidade(quant);
            stores[i].LojaPreco(price);
            i++;
        }
        else
        {
            System.err.println("Input incorrectly formatted: " + inputOfFile);
        }
    }catch (NumberFormatException e) {
        System.err.println("Error when trying to parse: " + inputOfFile);
    }
}

My guess is there is an extra new line character or something inside the file you are reading from. The above should be able to handle your file quite easily. Another plus to this implementation is that it will continue to read from the file even if you run into places in the file where the data is incorrectly formatted.