Converting Hexadecimal String to Decimal Integer

Question

I wrote some code to convert my hexadecimal display string to decimal integer  However  when input is something like 100a or 625b  something with letter  I got an error like this             java lang NumberFormatException  For input string    100a     at   java lang NumberFormatException forInputString Unknown Source     at   java lang Integer parseInt Unknown Source    Do you have any idea how can I convert my string with letters to decimal integer   if display getText      null        if display getText   contains  a      display getText   contains  b              display getText   contains  c      display getText   contains  d              display getText   contains  e     display getText   contains  f                     temp1   Integer parseInt display getText    16           temp1    double  temp1            else               temp1   Double parseDouble String valueOf display getText

User · Answer

Well  Mr ajb has resolved and pointed out the error in your code   Coming to the second part of the code  that is  converting a string with letters to decimal integer below is code for that   import java util Scanner   public class HexaToDecimal      int number      void getValue              Scanner sc   new Scanner System in         System out println  Please enter hexadecimal to convert            number   Integer parseInt sc nextLine    16         sc close             void toConvert              String decimal   Integer toString number         System out println  The Decimal value is       decimal            public static void main String   args             HexaToDecimal htd   new HexaToDecimal          htd getValue          htd toConvert             You can refer example on hexadecimal to decimal for more information

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void htod String hexadecimal        int h   hexadecimal length   - 1      int d   0      int n   0       for int i   0  i lt hexadecimal length    i                  char ch   hexadecimal charAt i           boolean flag   false          switch ch                        case  1   n   1  break              case  2   n   2  break              case  3   n   3  break              case  4   n   4  break              case  5   n   5  break              case  6   n   6  break              case  7   n   7  break              case  8   n   8  break              case  9   n   9  break              case  A   n   10  break              case  B   n   11  break              case  C   n   12  break              case  D   n   13  break              case  E   n   14  break              case  F   n   15  break              default   flag   true                    if flag                        System out println  Wrong Entry                 break                    d    int  n  Math pow 16 h       int d          h--            System out println  The decimal form of hexadecimal number   hexadecimal   is     d

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Scanner sc   new Scanner System in       System out println  Enter the value        String s   sc next          String s    AD       String s1   s toUpperCase        int power   0      double result   0            char   c   s1 toCharArray        for  int i   c length-1  i  gt  0    i--            boolean a   true          switch c i            case  A   c i    10  a   false  break          case  B   c i    11  a   false  break          case  C   c i    12  a   false  break          case  D   c i    13  a   false  break          case  E   c i    14  a   false  break          case  F   c i    15  a   false  break                      if a  true               result   result    c i -48    Math pow 16  power             else              result   result    c i     Math pow 16  power                         System out println result

User · Answer

You could take advantage of ASCII value for each letter and take off 55  easy and fast  int asciiOffset   55  char hex   Character toUpperCase  A        Only A-F uppercase int val   hex - asciiOffset  System out println  quot hexadecimal  quot    hex   System out println  quot decimal  quot    val    Output  hexadecimal A decimal 10

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public class Hex2Decimal    public static void hexDec String num        int sum 0      int newnum   0      String digit   num toUpperCase        for int i 0 i lt digit length   i                  char c   digit charAt digit length  -i-1            if c   A                         newnum   10                     else if c   B                         newnum   11                     if c   C                         newnum   12                     if c   D                         newnum   13                     if c   E                         newnum   14                     if c   F                         newnum   15                     else                       newnum   Character getNumericValue c                     sum    int   sum   newnum Math pow 16 i                 System out println   HexaDecimal to Decimal conversion is    sum          public static void main String   args     hexDec  9F

User · Answer

Since there is no brute-force approach which  done with it manualy   To know what exactly happened   Given a hexadecimal number      K K  1K  2    K2K1K0   The equivalent decimal value is      K    16    K  1   16  1   K  2   16  2          K2   162   K1   161   K0   160   For example  the hex number AB8C is       10   163   11   162   8   161   12   160   43916   Implementation      convert hex to decimal number private static int hexToDecimal String hex        int decimalValue   0      for  int i   0  i  lt  hex length    i              char hexChar   hex charAt i           decimalValue   decimalValue   16   hexCharToDecimal hexChar             return decimalValue    private static int hexCharToDecimal char character        if  character  gt    A   amp  amp  character  lt    F           return 10   character -  A       else   character is  0    1        9          return character -  0

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This is my solution   public static int hex2decimal String s        int val   0      for  int i   0  i  lt  s length    i              char c   s charAt i           int num    int  c          val   256 val   num            return val      For example to convert 3E8 to 1000   StringBuffer sb   new StringBuffer    sb append  char  0x03   sb append  char  0xE8   int n   hex2decimal sb toString     System out println n     will print 1000

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This is a little library that should help you with hexadecimals in Java  https   github com PatrykSitko HEX4J  It can convert from and to hexadecimals  It supports    byte boolean char char   String short int long float double  signed and unsigned    With it  you can convert your String to hexadecimal and the hexadecimal to a float double   Example    String hexValue   HEX4J Hexadecimal from String  Hello World    double doubleValue   HEX4J Hexadecimal to Double hexValue

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It looks like there s an extra space character in your string   You can use trim   to remove leading and trailing whitespaces   temp1   Integer parseInt display getText   trim    16      Or if you think the presence of a space means there s something else wrong  you ll have to look into it yourself  since we don t have the rest of your code

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public static int hex2decimal String s                 String digits    0123456789ABCDEF                s   s toUpperCase                 int val   0               for  int i   0  i  lt  s length    i                       char c   s charAt i                    int d   digits indexOf c                    val   16 val   d                              return val               That s the most efficient and elegant solution I have found over the internet  Some of the others solutions provided here didn t always work for me

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My way   private static int hexToDec String hex        return Integer parseInt hex  16

User · Answer

Google got me here  so i am updating this late for other to find when searching  A much simpler way is to use BigInteger  like so  BigInteger  quot 625b quot   16

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package com javatutorialhq tutorial   import java util Scanner        Java code convert hexadecimal to decimal     public class HexToDecimal        public static void main String   args                TODO Auto-generated method stub           System out print  Hexadecimal Input                 read the hexadecimal input from the console           Scanner s   new Scanner System in             String inputHex   s nextLine             try       actual conversion of hex to decimal              Integer outputDecimal   Integer parseInt inputHex  16                System out println  Decimal Equivalent     outputDecimal                        catch NumberFormatException ne                   Printing a warning message if the input is not a valid hex number              System out println  Invalid Input                         finally  s close

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You can use this method to get the digit   public int digitToValue char c        c  gt     amp    amp  amp  c  lt    9   return c -  0      else if  c  gt    A   amp  amp  c  lt    F   return 10   c -  A      else if  c  gt    a   amp  amp  c  lt    f   return 10   c -  a      return -1

[java] Converting Hexadecimal String to Decimal Integer

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