如何在不使用map的情况下在java上压缩字符串

public class StringCompression {
    public static String compressString(String input) {
        if (input == null || input.isEmpty()) {
            return input;
        }

        StringBuilder compressedString = new StringBuilder();
        int count = 1;
        int length = input.length();

        for (int i = 0; i < length; i++) {
            if (i < length - 1 && input.charAt(i) == input.charAt(i + 1)) {
                count++;
            } else {
                compressedString.append(input.charAt(i)).append(count);
                count = 1;
            }
        }

        return compressedString.length() < length ? compressedString.toString() : input;
    }

    public static void main(String[] args) {
        String input = "aabbbccccdd";
        String compressedString = compressString(input);
        System.out.println(compressedString);  // Output: "a2b3c4d2"
    }
}