Converting A String To Hexadecimal In Java

Question

I am trying to convert a string like \"testing123\" into hexadecimal form in java. I am currently using BlueJ.

And to convert it back, is it the same thing except b

Answer 1

First convert it into bytes using getBytes() function and then convert it into hex usign this :

private static String hex(byte[] bytes) {
    StringBuilder sb = new StringBuilder();
    for (int i=0; i<bytes.length; i++) {
        sb.append(String.format("%02X ",bytes[i]));
    }
    return sb.toString();
}

Answer 2

Convert String to Hexadecimal:

public String hexToString(String hex) {
    return Integer.toHexString(Integer.parseInt(hex));
}

definitely this is the easy way.

Answer 3

A short and convenient way to convert a String to its Hexadecimal notation is:

public static void main(String... args){
String str = "Hello! This is test string.";
char ch[] = str.toCharArray();
StringBuilder sb = new StringBuilder();
    for (int i = 0; i < ch.length; i++) {
        sb.append(Integer.toHexString((int) ch[i]));
    }
    System.out.println(sb.toString());
}

Answer 4

Much better:

public static String fromHexString(String hex, String sourceEncoding ) throws  IOException{
    ByteArrayOutputStream bout = new ByteArrayOutputStream();
    byte[] buffer = new byte[512];
    int _start=0;
    for (int i = 0; i < hex.length(); i+=2) {
        buffer[_start++] = (byte)Integer.parseInt(hex.substring(i, i + 2), 16);
        if (_start >=buffer.length || i+2>=hex.length()) {
            bout.write(buffer);
            Arrays.fill(buffer, 0, buffer.length, (byte)0);
            _start  = 0;
        }
    }

    return  new String(bout.toByteArray(), sourceEncoding);
}

Answer 5

Use DatatypeConverter.printHexBinary():

public static String toHexadecimal(String text) throws UnsupportedEncodingException
{
    byte[] myBytes = text.getBytes("UTF-8");

    return DatatypeConverter.printHexBinary(myBytes);
}

Example usage:

System.out.println(toHexadecimal("Hello StackOverflow"));

Prints:

48656C6C6F20537461636B4F766572666C6F77

Note: This causes a little extra trouble with Java 9 and newer since the API is not included by default. For reference e.g. see this GitHub issue.

Answer 6

check this solution for String to hex and hex to String vise-versa

public class TestHexConversion {
public static void main(String[] args) {
    try{
        String clearText = "testString For;0181;with.love";
        System.out.println("Clear Text  = " + clearText);
        char[] chars = clearText.toCharArray();
        StringBuffer hex = new StringBuffer();
        for (int i = 0; i < chars.length; i++) {
            hex.append(Integer.toHexString((int) chars[i]));
        }
        String hexText = hex.toString();
        System.out.println("Hex Text  = " + hexText);
        String decodedText = HexToString(hexText);
        System.out.println("Decoded Text = "+decodedText);
    } catch (Exception e){
        e.printStackTrace();
    }
}

public static String HexToString(String hex){

      StringBuilder finalString = new StringBuilder();
      StringBuilder tempString = new StringBuilder();

      for( int i=0; i<hex.length()-1; i+=2 ){
          String output = hex.substring(i, (i + 2));
          int decimal = Integer.parseInt(output, 16);
          finalString.append((char)decimal);
          tempString.append(decimal);
      }
    return finalString.toString();
}

Output as follows :

Clear Text = testString For;0181;with.love

Hex Text = 74657374537472696e6720466f723b303138313b776974682e6c6f7665

Decoded Text = testString For;0181;with.love