递归解压缩使用RLE压缩的字符串

Question

I'm trying to write a method that decompresses a string that was compressed using the RLE format recursively. So, I want a method that converts "5a2*3h32" into "aaaaa**hhh222".

Input: 5a2*3h32

Output: aaaaa**hhh222 --> this is correct

Input: i24 (should be: i44)

Output: Exception in thread "main" java.lang.NumberFormatException: For input string: "i"

So basically it doesn't like when a character is not preceded by a digit. However, if the input had one lone character at the end of the string, the method works fine.

I can't seem to figure this out. Any input would be really helpful!

public static String decompress(String compressedText){
    char c = ' ';
    String temp;

    if(compressedText.length() != 1){
        c = compressedText.charAt(1);
    }if(compressedText.length() == 1){
        return compressedText;       
    }else if(compressedText.charAt(0) == '0' && compressedText.length() != 2){
        return decompress(compressedText.substring(2));
    }else if(compressedText.charAt(0) == '0' && compressedText.length() == 2){
        compressedText = "\0";
        return compressedText;
    }else if(Character.isLetterOrDigit(c) == true || Character.isLetterOrDigit(c) == false){
        int i = Integer.parseInt(compressedText.substring(0,1));
        i = i-1;
        temp = Integer.toString(i);
        return c + decompress(temp.concat(compressedText.substring(1)));
    }if(Character.isLetter(c) == false){
        c = compressedText.charAt(2);
        int i = Integer.parseInt(compressedText.substring(0,2));
        i = i-1;
        temp = Integer.toString(i);
        return c + decompress(temp.concat(compressedText.substring(2)));
    }
    return compressedText;
}

Answer 1

As I commented the problem was with your condition, I change it a little bit and now it is working:

public static String decompress(String compressedText){
    char c = ' ';
    String temp;

    if(compressedText.length() != 1){
        c = compressedText.charAt(1);
    }if(compressedText.length() == 1){
        return compressedText;       
    }else if(compressedText.charAt(0) == '0' && compressedText.length() != 2){
        return decompress(compressedText.substring(2));
    }else if(compressedText.charAt(0) == '0' && compressedText.length() == 2){
        compressedText = "\0";
        return compressedText;
    }else if(Character.isDigit(compressedText.charAt(0)) == true){
        int i = Integer.parseInt(compressedText.substring(0,1));
        i = i-1;
        temp = Integer.toString(i);
        return c + decompress(temp.concat(compressedText.substring(1)));
    }
    return compressedText.charAt(0)+decompress(compressedText.substring(1));
}

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