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W1ll
Asked: 2020-01-31 11:10:46 +0800 CST 2020-01-31 11:10:46 +0800 CST

How to convert a string array to hexadecimal pairs and leading zeros

  • 772

I need to convert a string arrayto pares hexadecimalesfor each byte, zero separating each pair and completados con ceros a la izquierdaif necessary.

Using my code I get this:

41 54 2B 43 53 51 C A

But I need this:

41 54 2B 43 53 51 0C 0A

This is my code:

 public class StringToHex {

    public String convertStringToHex(String str) {

        char[] chars = str.toCharArray();

        StringBuffer hex = new StringBuffer();
        for (int i = 0; i < chars.length; i++) {
            hex.append( Integer.toHexString( (int)  chars[i]).toUpperCase());
            if (hex.length() < 2) {
                hex.insert(1, '0');
            }
            hex.append(" ");
        }
        return hex.toString();
    }
}

But it doesn't seem to work, can you tell me what is my mistake?

java

3 Answers

  1. Best Answer

    You can add a "0" when you detect that the length of the element to print is 1:

     if(Integer.toHexString( (int)  chars[i]).length()==1){
                hex.append("0");
 }

    This would be done as follows:

    public static String convertStringToHex(String str) {

    char[] chars = str.toCharArray();

    StringBuffer hex = new StringBuffer();
    for (int i = 0; i < chars.length; i++) {

        //Agrega un 0 a valores hexadecimales con un digito
        if(Integer.toHexString( (int)  chars[i]).length()==1){
            hex.append("0");
        }

        hex.append( Integer.toHexString( (int)  chars[i]).toUpperCase());        
        if (hex.length() < 2) {
            hex.insert(1, '0');
        }
        hex.append(" ");
    }


    return hex.toString();
}

    Example :

    System.out.println("::" + convertStringToHex("W1ll ?"));

    Without the change we would get 57 31 6C 6C C 3Fbut now the output would be:

    57 31 6C 6C 0C 3F
    • 1

  2. This is my solution.

    public static String convertStringToHex(String str) {

    char[] chars = str.toCharArray();

    StringBuffer hex = new StringBuffer();
    for (int i = 0; i < chars.length; i++) {

        //System.out.println(hex.length());
        if (Integer.toHexString((int) chars[i]).toUpperCase().length() < 2) {
            hex.append('0');
            hex.append(Integer.toHexString((int) chars[i]).toUpperCase());
        } else {
            hex.append(Integer.toHexString((int) chars[i]).toUpperCase());
        }
        hex.append(" ");
    }
    return hex.toString();
}

    It turns out that the condition that it is only one character that you had considered everything that you already had in Stringit, so after the first iteration it was never going to be less than 2, I solved it by comparing the converted character and verifying that it is 1, in that case then add a 0 in front and then add the value HEX, I hope it works for you, greetings.

    • 1

  3. Try using the String.format method to do the conversion and keep the formatting according to your needs.

    public static void main(String[] args) {

    System.out.println(toHex("hello world"));

}

public static String toHex(String source){
    StringBuilder builder = new StringBuilder();
    for(int i=0;i<source.length();i++){
        builder.append(String.format("%02x ",(int)source.charAt(i)));
    }
    return builder.toString();
}
    • 0