Java如何从具有多个字符串和双精度值的文本文件中读取一行？

Question

I want to create a program that reads from a text file with three different parts and then outputs the name. Eg text file:

vanilla   12   24
chocolate   23  20
chocolate chip  12   12

However, there is a bit of an issue on the third line, as there is a space. So far, my code works for the first two lines, but then throws a InputMismatchException on the third one. How do I make it so it reads both words from one line and then outputs it? My relevant code:

    while (in.hasNext())
{
    iceCreamFlavor = in.next();
    iceCreamRadius = in.nextDouble();
    iceCreamHeight = in.nextDouble();

out.println("Ice Cream: " + iceCreamFlavor);
}

Answer 1

In your input file, the separator between fields is composed of multiples spaces, no ? if yes, you could simply use split method of String object.

You read a line. You split it to obtain a String array.

String[] splitString = myString.split("   ");

Ther first element «0» is the String, the two others can be parsed as double

This could looks like :

    try (BufferedReader br = new BufferedReader(new FileReader("path/to/the/file.txt"))) {
        String line;
        while ((line = br.readLine()) != null) {
            String[] lineSplitted = line.split("   ");
            String label = lineSplitted[0];
            double d1 = Double.parseDouble(lineSplitted[1]);
            double d2 = Double.parseDouble(lineSplitted[2]);
        }

    } catch (IOException e) {
        e.printStackTrace();
    }

Answer 2

You can use scanner.useDelimiter to change the delimiter or use a regular expression to parse the line.

//sets delimiter to 2 or more consecutive spaces
Scanner s = new Scanner(input).useDelimiter("(\\s){2-}");

Check the Scanner Javadoc for examples: