以逗号分隔的文本文件到数组

Question

I have a text file with multiple lines, and 3 comma delimited entries per line.

Example:

Soviet Union,Larisa_LATYNINA,18
United States,Michael_PHELPS,16
Soviet Union,Nikolay_ANDRIANOV,15

I'm trying to separate them into 3 arrays, with 1 for the country, 1 for the person, and 1 for the medals.

        ArrayList<String> country = new ArrayList<>();
        ArrayList<String> name = new ArrayList<>();
        ArrayList<Integer> medals = new ArrayList<>();
        java.io.File file = new java.io.File("Olympics.txt");
        Scanner input = new Scanner(file);
        input.useDelimiter(" , ");
        while(input.hasNext()) {
            country.add(input.next());
            name.add(input.next());
            medals.add(input.nextInt());
        }

but I get a error every time I try to run it. I'm not exactly sure how to separate each "column" in the file into their own array.

If I use useDelimiter(","); instead of useDelimiter(" , "); I am getting the follow exception:

Exception in thread "main" java.util.InputMismatchException
at java.base/java.util.Scanner.throwFor(Scanner.java:939)
at java.base/java.util.Scanner.next(Scanner.java:1594)
at java.base/java.util.Scanner.nextInt(Scanner.java:2258)
at java.base/java.util.Scanner.nextInt(Scanner.java:2212)
at OlympicWinners.main(OlympicWinners.java:14)

This is the error I get. Line 14 is

Medals.add(input.nextInt());

Answer 1

From your text sample, the delimiter isn't a comma surrounded with spaces ( " , " ), but just a comma ( "," ). Remove those spaces and you should be OK:

input.useDelimiter(",");

Answer 2

You are getting InputMismatchException because of the last line input.nextInt() returns

"18 
United States"

Since there is no , delimiter between 18 and United States (but there is line separator \\n ) each token is returned from delimiter to delimiter.

You should read all lines from file and split them by separator:

List<String> lines = Files.readAllLines(Paths.get("Olympic.txt"));

for (String line : lines) {
    String[] fields = line.split(",");
    country.add(fields[0]);
    name.add(fields[1]);
    medals.add(Integer.valueOf(fields[2]));
}

Answer 3

Please modify your code to this :

public class Main {

    public static void main(String[] args) throws FileNotFoundException {
        ArrayList<String> country = new ArrayList<>();
        ArrayList<String> name = new ArrayList<>();
        ArrayList<Integer> medals = new ArrayList<>();
        BufferedReader reader;
        try {
            reader = new BufferedReader(new FileReader("F://test.txt"));
            String line = reader.readLine();
            while (line != null) {
                String[] lineParts = line.split(",");
                country.add(lineParts[0]);
                name.add(lineParts[1]); 
                medals.add(Integer.valueOf(lineParts[2]));
                line = reader.readLine();
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println(country);
        System.out.println(name);
        System.out.println(medals);

    }

}

In test.xml :

Soviet Union,Larisa_LATYNINA,18
United States,Michael_PHELPS,16
Soviet Union,Nikolay_ANDRIANOV,15

Output of the code :

[Soviet Union, United States, Soviet Union]
[Larisa_LATYNINA, Michael_PHELPS, Nikolay_ANDRIANOV]
[18, 16, 15]