如何读取 java 中字符之间的多个标记？

Question

I am doing a project where I need to read multiple lines that contains user data from a txt file. This data will create a profile.

For example:

name,lastname,email,hobbies1;hobbies2...hobbiesN,activity1;activity2...activityN

name2,lastname2,email.... and so on

I don't know how many hobbies or activities are there so I have to set them into an array. All of variables are on one line. I tried using delimiter and split, but when I move onto the next line I get inputMismatchException.

Answer 1

Simplest way is to change the format.

Instead of separating every field with , try using ; for separating different types of attributes and , for elements of arrays. The end result will be something like:

name; lastname; email; hobbies1, hobbies2, ..., hobbiesN; activity1, activity2, ..., activityN

First you split the String using ; as delimiter, then for those fields that allows for arrays you divide the array in its elements by splitting that sub String with , as delimiter.

Answer 2

Read lines, then split on comma, and split on semi-colon where needed.

Don't use Scanner for line-reading a file.

try (BufferedReader in = Files.newBufferedReader(Paths.get("test.txt"))) {
    for (String line; (line = in.readLine()) != null; ) {
        String[] fields = line.split(",");
        String   name =       (fields.length >= 1 ? fields[0] : "");
        String   lastname =   (fields.length >= 2 ? fields[1] : "");
        String   email =      (fields.length >= 3 ? fields[2] : "");
        String[] hobbies =    (fields.length >= 4 ? fields[3].split(";") : new String[0]);
        String[] activities = (fields.length >= 5 ? fields[4].split(";") : new String[0]);
        System.out.println("name=" + name +
                         ", lastname=" + lastname +
                         ", email=" + email +
                         ", hobbies=" + Arrays.toString(hobbies) +
                         ", activities=" + Arrays.toString(activities));
    }
}

test.txt

name,lastname,email,hobbies1;hobbies2...hobbiesN,activity1;activity2...activityN
name2,lastname2,email

Output

name=name, lastname=lastname, email=email, hobbies=[hobbies1, hobbies2...hobbiesN], activities=[activity1, activity2...activityN]
name=name2, lastname=lastname2, email=email, hobbies=[], activities=[]