如何使用扫描仪基于正则表达式将值分配给多个变量

Question

I am getting input from console using Scanner. Expected input format is CR127-0772. I would like to extract 3 different values from that input: first one is string 'CR', second one is 127 and third one is 0072. This can be performed in C using scanf

scanf("%s%d-%d", &st, &a, &b)

How can I do same task using java? I don't see how I can use regex with Scanner. Your help is much appreciated.

Answer 1

You can just scan it to a string, then set the variables to substrings of that string (parsed for ints as necessary).

String s = scanner.nextLine();
String st = s.substring(0,2);
int a = Integer.parseInt(s.substring(2,5));
int b = Integer.parseInt(s.substring(6));

This does assume that the string is always two characters and the first int is always three digits. The second int can be arbitrarily long.

Answer 2

Firstly, Java couldn't do it, because java doesn't use pointers. The best you could hope for is a method that returns a list/array of values.

Secondly, "no"; there's nothing similar in the JDK that does this kind of thing.

However, you can do it fairly simply in as many lines of code as you have variables:

String input = "CR127-0772"; // given this got from console

String st = input.replaceAll("\\d.*", ""); // delete from 1st digit onwards
String a = input.replaceAll("^\\D+|-.*", ""); // delete leading non-digits or dash onwards
String b = input.replaceAll(".*-", ""); // delete everything up to a dash

This uses regex to match what you don't want and "delete" it by replacing with a blank.

Answer 3

That's not possible using Scanner since this class works with a single delimiter. What you should do here is manually parse the String with a desired format.

Here's an example of how to do this:

String data = scanner.nextLine();
String stringPart = data.replaceAll("[^a-zA-Z]", ""); //remove all non letter chars
int[] numbers = Arrays.stream( //convert to Stream the result of
    data.replaceAll("[a-zA-Z]", "") // remove all letter chars
        .split("-")                 // and split by "-"
    ).mapToInt(Integer::parseInt) //map the array of String to a stream of int (not Integer)
    .toArray(); //convert the stream into an array int[]