Converting A String To Hexadecimal In Java
JavaStringHexJava Problem Overview
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 backward?
Java Solutions
Solution 1 - Java
Here's a short way to convert it to hex:
public String toHex(String arg) {
return String.format("%040x", new BigInteger(1, arg.getBytes(/*YOUR_CHARSET?*/)));
}
Solution 2 - Java
To ensure that the hex is always 40 characters long, the BigInteger has to be positive:
public String toHex(String arg) {
return String.format("%x", new BigInteger(1, arg.getBytes(/*YOUR_CHARSET?*/)));
}
Solution 3 - Java
import org.apache.commons.codec.binary.Hex;
...
String hexString = Hex.encodeHexString(myString.getBytes(/* charset */));
http://commons.apache.org/codec/apidocs/org/apache/commons/codec/binary/Hex.html
Solution 4 - Java
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.
Solution 5 - Java
The numbers that you encode into hexadecimal must represent some encoding of the characters, such as UTF-8. So first convert the String to a byte[] representing the string in that encoding, then convert each byte to hexadecimal.
public static String hexadecimal(String input, String charsetName) throws UnsupportedEncodingException {
if (input == null) throw new NullPointerException();
return asHex(input.getBytes(charsetName));
}
private static final char[] HEX_CHARS = "0123456789abcdef".toCharArray();
public static String asHex(byte[] buf)
{
char[] chars = new char[2 * buf.length];
for (int i = 0; i < buf.length; ++i)
{
chars[2 * i] = HEX_CHARS[(buf[i] & 0xF0) >>> 4];
chars[2 * i + 1] = HEX_CHARS[buf[i] & 0x0F];
}
return new String(chars);
}
Solution 6 - Java
Here an other solution
public static String toHexString(byte[] ba) {
StringBuilder str = new StringBuilder();
for(int i = 0; i < ba.length; i++)
str.append(String.format("%x", ba[i]));
return str.toString();
}
public static String fromHexString(String hex) {
StringBuilder str = new StringBuilder();
for (int i = 0; i < hex.length(); i+=2) {
str.append((char) Integer.parseInt(hex.substring(i, i + 2), 16));
}
return str.toString();
}
Solution 7 - Java
All answers based on String.getBytes() involve encoding your string according to a Charset. You don't necessarily get the hex value of the 2-byte characters that make up your string. If what you actually want is the equivalent of a hex viewer, then you need to access the chars directly. Here's the function that I use in my code for debugging Unicode issues:
static String stringToHex(String string) {
StringBuilder buf = new StringBuilder(200);
for (char ch: string.toCharArray()) {
if (buf.length() > 0)
buf.append(' ');
buf.append(String.format("%04x", (int) ch));
}
return buf.toString();
}
Then, stringToHex("testing123") will give you:
0074 0065 0073 0074 0069 006e 0067 0031 0032 0033
Solution 8 - Java
To get the Integer value of hex
//hex like: 0xfff7931e to int
int hexInt = Long.decode(hexString).intValue();
Solution 9 - Java
I would suggest something like this, where str is your input string:
StringBuffer hex = new StringBuffer();
char[] raw = tokens[0].toCharArray();
for (int i=0;i<raw.length;i++) {
if (raw[i]<=0x000F) { hex.append("000"); }
else if(raw[i]<=0x00FF) { hex.append("00" ); }
else if(raw[i]<=0x0FFF) { hex.append("0" ); }
hex.append(Integer.toHexString(raw[i]).toUpperCase());
}
Solution 10 - Java
byte[] bytes = string.getBytes(CHARSET); // you didn't say what charset you wanted
BigInteger bigInt = new BigInteger(bytes);
String hexString = bigInt.toString(16); // 16 is the radix
You could return hexString at this point, with the caveat that leading null-chars will be stripped, and the result will have an odd length if the first byte is less than 16. If you need to handle those cases, you can add some extra code to pad with 0s:
StringBuilder sb = new StringBuilder();
while ((sb.length() + hexString.length()) < (2 * bytes.length)) {
sb.append("0");
}
sb.append(hexString);
return sb.toString();
Solution 11 - Java
Convert a letter in hex code and hex code in letter.
String letter = "a";
String code;
int decimal;
code = Integer.toHexString(letter.charAt(0));
decimal = Integer.parseInt(code, 16);
System.out.println("Hex code to " + letter + " = " + code);
System.out.println("Char to " + code + " = " + (char) decimal);
Solution 12 - Java
To go the other way (hex to string), you can use
public String hexToString(String hex) {
return new String(new BigInteger(hex, 16).toByteArray());
}
Solution 13 - Java
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();
}
Solution 14 - Java
Using Multiple Peoples help from multiple Threads..
I know this has been answered, but i would like to give a full encode & decode method for any others in my same situation..
Here's my Encoding & Decoding methods..
// Global Charset Encoding
public static Charset encodingType = StandardCharsets.UTF_8;
// Text To Hex
public static String textToHex(String text)
{
byte[] buf = null;
buf = text.getBytes(encodingType);
char[] HEX_CHARS = "0123456789abcdef".toCharArray();
char[] chars = new char[2 * buf.length];
for (int i = 0; i < buf.length; ++i)
{
chars[2 * i] = HEX_CHARS[(buf[i] & 0xF0) >>> 4];
chars[2 * i + 1] = HEX_CHARS[buf[i] & 0x0F];
}
return new String(chars);
}
// Hex To Text
public static String hexToText(String hex)
{
int l = hex.length();
byte[] data = new byte[l / 2];
for (int i = 0; i < l; i += 2)
{
data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
+ Character.digit(hex.charAt(i + 1), 16));
}
String st = new String(data, encodingType);
return st;
}
Solution 15 - Java
One line HEX encoding/decoding without external libs (Java 8 and above):
Encoding :
String hexString = inputString.chars().mapToObj(c ->
Integer.toHexString(c)).collect(Collectors.joining());
Decoding :
String decodedString = Stream.iterate(0, i -> i+2)
.limit(hexString.length()/2 + Math.min(hexString.length()%2,1))
.map(i -> "" + (char)Integer.parseInt("" + hexString.charAt(i) + hexString.charAt(i+1),16))
.collect(Collectors.joining());
Solution 16 - Java
[Convert String to Hexadecimal][1]:
public String hexToString(String hex) {
return Integer.toHexString(Integer.parseInt(hex));
}
definitely this is the easy way. [1]: http://
Solution 17 - Java
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);
}
Solution 18 - Java
import java.io.*;
import java.util.*;
public class Exer5{
public String ConvertToHexadecimal(int num){
int r;
String bin="\0";
do{
r=num%16;
num=num/16;
if(r==10)
bin="A"+bin;
else if(r==11)
bin="B"+bin;
else if(r==12)
bin="C"+bin;
else if(r==13)
bin="D"+bin;
else if(r==14)
bin="E"+bin;
else if(r==15)
bin="F"+bin;
else
bin=r+bin;
}while(num!=0);
return bin;
}
public int ConvertFromHexadecimalToDecimal(String num){
int a;
int ctr=0;
double prod=0;
for(int i=num.length(); i>0; i--){
if(num.charAt(i-1)=='a'||num.charAt(i-1)=='A')
a=10;
else if(num.charAt(i-1)=='b'||num.charAt(i-1)=='B')
a=11;
else if(num.charAt(i-1)=='c'||num.charAt(i-1)=='C')
a=12;
else if(num.charAt(i-1)=='d'||num.charAt(i-1)=='D')
a=13;
else if(num.charAt(i-1)=='e'||num.charAt(i-1)=='E')
a=14;
else if(num.charAt(i-1)=='f'||num.charAt(i-1)=='F')
a=15;
else
a=Character.getNumericValue(num.charAt(i-1));
prod=prod+(a*Math.pow(16, ctr));
ctr++;
}
return (int)prod;
}
public static void main(String[] args){
Exer5 dh=new Exer5();
Scanner s=new Scanner(System.in);
int num;
String numS;
int choice;
System.out.println("Enter your desired choice:");
System.out.println("1 - DECIMAL TO HEXADECIMAL ");
System.out.println("2 - HEXADECIMAL TO DECIMAL ");
System.out.println("0 - EXIT ");
do{
System.out.print("\nEnter Choice: ");
choice=s.nextInt();
if(choice==1){
System.out.println("Enter decimal number: ");
num=s.nextInt();
System.out.println(dh.ConvertToHexadecimal(num));
}
else if(choice==2){
System.out.println("Enter hexadecimal number: ");
numS=s.next();
System.out.println(dh.ConvertFromHexadecimalToDecimal(numS));
}
}while(choice!=0);
}
}
Solution 19 - Java
new BigInteger(1, myString.getBytes(/*YOUR_CHARSET?*/)).toString(16)
Solution 20 - Java
Here are some benchmarks comparing different approaches and libraries. Guava beats Apache Commons Codec at decoding. Commons Codec beats Guava at encoding. And JHex beats them both for decoding and encoding.
JHex example
String hexString = "596f752772652077656c636f6d652e";
byte[] decoded = JHex.decodeChecked(hexString);
System.out.println(new String(decoded));
String reEncoded = JHex.encode(decoded);
Everything is in a single class file for JHex. Feel free to copy paste if you don't want yet another library in your dependency tree. Also note, it is only available as Java 9 jar until I can figure out how to publish multiple release targets with Gradle and the Bintray plugin.
Solution 21 - Java
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
Solution 22 - Java
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());
}