Question

I am new to Java and looking for some help with Java’s Scanner class. Below is the problem.
I have a text file with multiple lines and each line having multiple pairs of digit.Such that each pair of digit is represented as ( digit,digit ). For example 3,3 6,4 7,9. All these multiple pairs of digits are seperated from each other by a whitespace. Below is an exampel from the text file.

1 2,3 3,2 4,5

2 1,3 4,2 6,13

3 1,2 4,2 5,5

What i want is that i can retrieve each digit seperately. So that i can create an array of linkedlist out it. Below is what i have acheived so far.

Scanner sc = new Scanner(new File("a.txt"));
    Scanner lineSc;
    String line;
    Integer vertix = 0;
    Integer length = 0;
    sc.useDelimiter("\\n"); // For line feeds

    while (sc.hasNextLine()) {
        line = sc.nextLine();
        lineSc = new Scanner(line);

        lineSc.useDelimiter("\\s"); // For Whitespace
        // What should i do here. How should i scan through considering the whitespace and comma
        }

Thanks

Answer 1

Consider using a regular expression, and data that doesn’t conform to your expectation will be easily identified and dealt with.

CharSequence inputStr = "2 1,3 4,2 6,13";    
String patternStr = "(\\d)\\s+(\\d),";    
// Compile and use regular expression
Pattern pattern = Pattern.compile(patternStr);
Matcher matcher = pattern.matcher(inputStr);

while (matcher.find()) {
    // Get all groups for this match
    for (int i=0; i<=matcher.groupCount(); i++) {
        String groupStr = matcher.group(i);
    }
}

Group one and group two will correspond to the first and second digit in each pairing, respectively.