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 backward

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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 gt 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

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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 lt raw length i          if      raw i  lt  0x000F    hex append  000          else if raw i  lt  0x00FF    hex append  00           else if raw i  lt  0x0FFF    hex append  0            hex append Integer toHexString raw i   toUpperCase

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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

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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

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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  lt  hex length    i  2            buffer  start       byte Integer parseInt hex substring i  i   2   16           if   start  gt  buffer length    i 2 gt  hex length                  bout write buffer               Arrays fill buffer  0  buffer length   byte 0                start    0                       return  new String bout toByteArray    sourceEncoding

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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

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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  lt  ch length  i              sb append Integer toHexString  int  ch i               System out println sb toString

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To get the Integer value of hex            hex like  0xfff7931e to int         int hexInt   Long decode hexString  intValue

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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     lt   2   bytes length       sb append  0      sb append hexString   return sb toString

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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 lt bytes length  i              sb append String format   02X   bytes i               return sb toString

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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    quot 596f752772652077656c636f6d652e quot   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

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new BigInteger 1  myString getBytes   YOUR CHARSET      toString 16

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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

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To go the other way  hex to string   you can use  public String hexToString String hex        return new String new BigInteger hex  16  toByteArray

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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    gt  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

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Using Multiple Peoples help from multiple Threads    I know this has been answered  but i would like to give a full encode  amp  decode method for any others in my same situation    Here s my Encoding  amp  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  lt  buf length    i                chars 2   i    HEX CHARS  buf i   amp  0xF0   gt  gt  gt  4           chars 2   i   1    HEX CHARS buf i   amp  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  lt  l  i    2                data i   2     byte    Character digit hex charAt i   16   lt  lt  4                Character digit hex charAt i   1   16              String st   new String data  encodingType       return st

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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  lt  buf length    i                chars 2   i    HEX CHARS  buf i   amp  0xF0   gt  gt  gt  4           chars 2   i   1    HEX CHARS buf i   amp  0x0F             return new String chars

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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    quot testString For 0181 with love quot           System out println  quot Clear Text     quot    clearText           char   chars   clearText toCharArray            StringBuffer hex   new StringBuffer            for  int i   0  i  lt  chars length  i                  hex append Integer toHexString  int  chars i                       String hexText   hex toString            System out println  quot Hex Text     quot    hexText           String decodedText   HexToString hexText           System out println  quot Decoded Text    quot  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 lt 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

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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

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Here an other solution  public static String toHexString byte   ba        StringBuilder str   new StringBuilder        for int i   0  i  lt  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  lt  hex length    i  2            str append  char  Integer parseInt hex substring i  i   2   16              return str toString

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Convert String to Hexadecimal   public String hexToString String hex        return Integer toHexString Integer parseInt hex        definitely this is the easy way

[java] Converting A String To Hexadecimal In Java

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