Question

For example, I have input String: “qwerty1qwerty2“;

As Output I would like have [1,2].

My current implementation below:

import java.util.ArrayList;
import java.util.List;

public class Test1 {

    public static void main(String[] args) {
        String inputString = args[0];
        String digitStr = "";
        List<Integer> digits = new ArrayList<Integer>();

        for (int i = 0; i < inputString.length(); i++) {
            if (Character.isDigit(inputString.charAt(i))) {
                digitStr += inputString.charAt(i);
            } else {
                if (!digitStr.isEmpty()) {
                    digits.add(Integer.parseInt(digitStr));
                    digitStr = "";
                }
            }
        }
        if (!digitStr.isEmpty()) {
            digits.add(Integer.parseInt(digitStr));
            digitStr = "";
        }

        for (Integer i : digits) {
            System.out.println(i);
        }
    }
}

But after double check I dislake couple points:

1. Some lines of code repeat twice.

2. I use List. I think it is not very good idea, better using array.

So, What do you think?

Could you please provide any advice?

Answer 1

Use replaceAll:

String str = "qwerty1qwerty2";      
str = str.replaceAll("[^0-9]+", " ");
System.out.println(Arrays.asList(str.trim().split(" ")));

Output:

[1, 2]

[EDIT]

If you want to include - a.e minus, add -?:

String str = "qwerty-1qwerty-2 455 f0gfg 4";      
str = str.replaceAll("[^-?0-9]+", " "); 
System.out.println(Arrays.asList(str.trim().split(" ")));

Output:

[-1, -2, 455, 0, 4]

---

Description

[^-?0-9]+

• + Between one and unlimited times, as many times as possible, giving back as needed
• -? One of the characters “-?”
• 0-9 A character in the range between “0” and “9”