Question

How to sort a string with digits and letters (digits before letters) in Java

Answer 1

import java.util.Arrays;

public class CustomSort {
    public static String customSort(String input) {
        Character[] chars = new Character[input.length()];
        for (int i = 0; i < input.length(); i++) {
            chars[i] = input.charAt(i);
        }

        Arrays.sort(chars, (a, b) -> {
            if (Character.isDigit(a) && !Character.isDigit(b)) return -1;  // Digits before letters
            if (!Character.isDigit(a) && Character.isDigit(b)) return 1; // Letters after digits
            return a.compareTo(b); // Maintain lexicographic order
        });

        StringBuilder sortedString = new StringBuilder();
        for (char ch : chars) {
            sortedString.append(ch);
        }

        return sortedString.toString();
    }

    public static void main(String[] args) {
        String input = "d2c4b3a1";
        String sortedInput = customSort(input);

        System.out.println("Custom sorted string: " + sortedInput);
    }
}


/*
run:

Custom sorted string: 1234abcd

*/

 

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