How can I convert byte size into a human-readable format in Java

Question

How can I convert byte size into a human-readable format in Java  Like 1024 should become  quot 1 Kb quot  and 1024 1024 should become  quot 1 Mb quot   I am kind of sick of writing this utility method for each project  Is there a static method in Apache Commons for this

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Fun fact  The original snippet posted here was the most copied Java snippet of all time on Stack Overflow  and it was flawed  It was fixed  but it got messy  Full story in this article  The most copied Stack Overflow snippet of all time is flawed   Source  Formatting byte size to human readable format   Programming Guide SI  1 k   1 000  public static String humanReadableByteCountSI long bytes        if  -1000  lt  bytes  amp  amp  bytes  lt  1000            return bytes    quot  B quot             CharacterIterator ci   new StringCharacterIterator  quot kMGTPE quot        while  bytes  lt   -999 950    bytes  gt   999 950            bytes    1000          ci next              return String format  quot   1f  cB quot   bytes   1000 0  ci current        Binary  1 Ki   1 024  public static String humanReadableByteCountBin long bytes        long absB   bytes    Long MIN VALUE   Long MAX VALUE   Math abs bytes       if  absB  lt  1024            return bytes    quot  B quot             long value   absB      CharacterIterator ci   new StringCharacterIterator  quot KMGTPE quot        for  int i   40  i  gt   0  amp  amp  absB  gt  0xfffccccccccccccL  gt  gt  i  i -  10            value  gt  gt   10          ci next              value    Long signum bytes       return String format  quot   1f  ciB quot   value   1024 0  ci current        Example output                                SI     BINARY                     0         0 B        0 B                   27        27 B       27 B                  999       999 B      999 B                 1000      1 0 kB     1000 B                 1023      1 0 kB     1023 B                 1024      1 0 kB    1 0 KiB                 1728      1 7 kB    1 7 KiB               110592    110 6 kB  108 0 KiB              7077888      7 1 MB    6 8 MiB            452984832    453 0 MB  432 0 MiB          28991029248     29 0 GB   27 0 GiB        1855425871872      1 9 TB    1 7 TiB  9223372036854775807      9 2 EB    8 0 EiB    Long MAX VALUE

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Here s a Go version  For simplicity  I ve only included the binary output case  func sizeOf bytes int64  string       const unit   1024     if bytes  lt  unit           return fmt Sprintf  quot  d B quot   bytes             fb    float64 bytes      exp    int math Log fb    math Log unit       pre     quot KMGTPE quot  exp-1      div    math Pow unit  float64 exp       return fmt Sprintf  quot   1f  ciB quot   fb   div  pre

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Use an Android built-in class For Android  there is a class  Formatter  Just one line of code and you are done  android text format Formatter formatShortFileSize activityContext  bytes    It is like formatFileSize    but trying to generate shorter numbers  showing fewer decimals   android text format Formatter formatFileSize activityContext  bytes    It formats a content size to be in the form of bytes  kilobytes  megabytes  etc

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This is a modified version of aioobe s answer   Changes    Locale parameter  because some languages use   and others   as decimal point  human-readable code      private static final String   SI UNITS      B    kB    MB    GB    TB    PB    EB     private static final String   BINARY UNITS      B    KiB    MiB    GiB    TiB    PiB    EiB      public static String humanReadableByteCount final long bytes  final boolean useSIUnits  final Locale locale        final String   units   useSIUnits   SI UNITS   BINARY UNITS      final int base   useSIUnits   1000   1024          When using the smallest unit no decimal point is needed  because it s the exact number      if  bytes  lt  base            return bytes         units 0              final int exponent    int   Math log bytes    Math log base        final String unit   units exponent       return String format locale     1f  s   bytes   Math pow base  exponent   unit

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Use the following function to get exact information  It is generated by taking the base of the ATM CashWithdrawl concept  getFullMemoryUnit    Total   123 MB   Max   1 GB  773 MB  512 KB   Free   120 MB  409 KB  304 Bytes   public static String getFullMemoryUnit long unit        long BYTE   1024  KB   BYTE  MB   KB   KB  GB   MB   KB  TB   GB   KB      long KILO BYTE  MEGA BYTE   0  GIGA BYTE   0  TERA BYTE   0      unit   Math abs unit       StringBuffer buffer   new StringBuffer        if   unit   TB  gt  0             TERA BYTE    int   unit   TB           buffer append TERA BYTE  quot  TB quot            unit -  TERA BYTE   TB            if   unit   GB  gt  0             GIGA BYTE    int   unit   GB           if  TERA BYTE    0  buffer append  quot    quot            buffer append GIGA BYTE  quot  GB quot            unit    GB            if   unit   MB  gt  0             MEGA BYTE    int   unit   MB           if  GIGA BYTE    0  buffer append  quot    quot            buffer append MEGA BYTE  quot  MB quot            unit    MB            if   unit   KB  gt  0             KILO BYTE    int   unit   KB           if  MEGA BYTE    0  buffer append  quot    quot            buffer append KILO BYTE  quot  KB quot            unit    KB            if   unit  gt  0   buffer append  quot    quot  unit  quot  Bytes quot        return buffer toString       I have just modified the code of facebookarchive-StringUtils to get the below format  The same format you will get when you use apache hadoop-StringUtils getMemoryUnit    Total   123 0 MB   Max   1 8 GB   Free   120 4 MB   public static String getMemoryUnit long bytes        DecimalFormat oneDecimal   new DecimalFormat  quot 0 0 quot        float BYTE   1024 0f  KB   BYTE  MB   KB   KB  GB   MB   KB  TB   GB   KB      long absNumber   Math abs bytes       double result   bytes      String suffix    quot  Bytes quot       if  absNumber  lt  MB            result   bytes   KB          suffix    quot  KB quot         else if  absNumber  lt  GB            result   bytes   MB          suffix    quot  MB quot         else if  absNumber  lt  TB            result   bytes   GB          suffix    quot  GB quot             return oneDecimal format result    suffix     Example usage of the above methods  public static void main String   args        Runtime runtime   Runtime getRuntime        int availableProcessors   runtime availableProcessors         long heapSize   Runtime getRuntime   totalMemory        long heapMaxSize   Runtime getRuntime   maxMemory        long heapFreeSize   Runtime getRuntime   freeMemory         System out format  quot Total    s   Max    s   Free    s  n quot   heapSize  heapMaxSize  heapFreeSize       System out format  quot getMemoryUnit    Total    s   Max    s   Free    s  n quot               getMemoryUnit heapSize   getMemoryUnit heapMaxSize   getMemoryUnit heapFreeSize        System out format  quot getFullMemoryUnit    Total    s   Max    s   Free    s  n quot               getFullMemoryUnit heapSize   getFullMemoryUnit heapMaxSize   getFullMemoryUnit heapFreeSize       Bytes to get the above format Total   128974848   Max   1884815360   Free   126248240   In order to display time in a human-readable format  use the function millisToShortDHMS long duration

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We can completely avoid using the slow Math pow   and Math log   methods without sacrificing simplicity since the factor between the units  for example  B  KB  MB  etc   is 1024 which is 2 10  The Long class has a handy numberOfLeadingZeros   method which we can use to tell which unit the size value falls in  Key point  Size units have a distance of 10 bits  1024   2 10  meaning the position of the highest one bit   or in other words the number of leading zeros   differ by 10  Bytes   KB 1024  KB   MB 1024  etc    Correlation between number of leading zeros and size unit    of leading 0 s   Size unit -------------------------------  gt 53                B  Bytes   gt 43                KB  gt 33                MB  gt 23                GB  gt 13                TB  gt 3                 PB  lt  2                EB  The final code  public static String formatSize long v        if  v  lt  1024  return v    quot  B quot       int z    63 - Long numberOfLeadingZeros v     10      return String format  quot   1f  sB quot    double v    1L  lt  lt   z 10     quot  KMGTPE quot  charAt z

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Maybe you can use this code  in C    long Kb   1024  long Mb   Kb   1024  long Gb   Mb   1024  long Tb   Gb   1024  long Pb   Tb   1024  long Eb   Pb   1024   if  size  lt  Kb   return size ToString      quot  byte quot    if  size  lt  Mb   return  size   Kb  ToString  quot        quot      quot  Kb  quot   if  size  lt  Gb   return  size   Mb  ToString  quot        quot      quot  Mb  quot   if  size  lt  Tb   return  size   Gb  ToString  quot        quot      quot  Gb  quot   if  size  lt  Pb   return  size   Tb  ToString  quot        quot      quot  Tb  quot   if  size  lt  Eb   return  size   Pb  ToString  quot        quot      quot  Pb  quot   if  size  gt   Eb  return  size   Eb  ToString  quot        quot      quot  Eb  quot    return  quot invalid size quot

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You can use StringUtils   s TraditionalBinarPrefix  public static String humanReadableInt long number        return TraditionalBinaryPrefix long2String number          1

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There is now one library available that contains unit formatting  I added it to the triava library  as the only other existing library seems to be one for Android   It can format numbers with arbitrary precision  in 3 different systems  SI  IEC  JEDEC  and various output options  Here are some code examples from the triava unit tests   UnitFormatter formatAsUnit 1126  UnitSystem SI   B          1 13kB  UnitFormatter formatAsUnit 2094  UnitSystem IEC   B          2 04KiB    Printing exact kilo  mega values  here with W   Watt    UnitFormatter formatAsUnits 12 000 678  UnitSystem SI   W                12MW  678W    You can pass a DecimalFormat to customize the output   UnitFormatter formatAsUnit 2085  UnitSystem IEC   B   new DecimalFormat  0 0000           2 0361KiB    For arbitrary operations on  kilo or mega values  you can split them into components   UnitComponent uc   new  UnitComponent 123 345 567 789L  UnitSystem SI   int kilos   uc kilo       567 int gigas   uc giga       123

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filename filedilg getSelectedFile   getAbsolutePath    File file new File filename    String disp FileUtils byteCountToDisplaySize file length     System out println  THE FILE PATH IS   file  THIS File SIZE IS IN MB   disp

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Try JSR 363  Its unit extension modules like Unicode CLDR  in GitHub  uom-systems  do all that for you  You can use MetricPrefix included in every implementation or BinaryPrefix  comparable to some of the examples above  and if you e g  live and work in India or a nearby country  IndianPrefix  also in the common module of uom-systems  allows you to use and format  quot Crore Bytes quot  or  quot Lakh Bytes quot   too

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If you use Android  you can simply use android text format Formatter formatFileSize    Alternatively  here s a solution based on this popular post             Formats the bytes to a human readable format            param si true if each kilo  1000  false if kilo  1024          SuppressLint  quot DefaultLocale quot     public static String humanReadableByteCount final long bytes  final boolean si          final int unit   si   1000   1024      if bytes lt unit        return bytes    quot  B quot        double result   bytes      final String unitsToUse    si    quot k quot     quot K quot      quot MGTPE quot       int i   0      final int unitsCount   unitsToUse length        while true              result    unit        if result  lt  unit          break           Check if we can go further        if i    unitsCount-1          break          i             final StringBuilder sb   new StringBuilder 9       sb append String format  quot   1f  quot   result        sb append unitsToUse charAt i        if si        sb append  B        else sb append  i   append  B        final String resultStr   sb toString        return resultStr       Or in Kotlin         formats the bytes to a human readable format        param si true if each kilo  1000  false if kilo  1024      SuppressLint  quot DefaultLocale quot   fun humanReadableByteCount bytes  Long  si  Boolean   String        val unit   if  si  1000 0 else 1024 0     if  bytes  lt  unit          return  quot  bytes B quot      var result   bytes toDouble       val unitsToUse    if  si   quot k quot  else  quot K quot      quot MGTPE quot      var i   0     val unitsCount   unitsToUse length     while  true            result    unit         if  result  lt  unit    i    unitsCount - 1              break           i           return with StringBuilder 9             append String format  quot   1f  quot   result           append unitsToUse i           if  si  append  B   else append  quot iB quot         toString

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Byte Units allows you to do it like this   long input1   1024  long input2   1024   1024   Assert assertEquals  1 KiB   BinaryByteUnit format input1    Assert assertEquals  1 MiB   BinaryByteUnit format input2     Assert assertEquals  1 024 KB   DecimalByteUnit format input1     0     Assert assertEquals  1 049 MB   DecimalByteUnit format input2     000      NumberFormat format   new DecimalFormat         Assert assertEquals  1 KiB   BinaryByteUnit format input1  format    Assert assertEquals  1 MiB   BinaryByteUnit format input2  format      I have written another library called storage-units that allows you to do it like this   String formattedUnit1   StorageUnits formatAsCommonUnit input1        String formattedUnit2   StorageUnits formatAsCommonUnit input2        String formattedUnit3   StorageUnits formatAsBinaryUnit input1   String formattedUnit4   StorageUnits formatAsBinaryUnit input2   String formattedUnit5   StorageUnits formatAsDecimalUnit input1     00   Locale GERMAN   String formattedUnit6   StorageUnits formatAsDecimalUnit input2     00   Locale GERMAN   String formattedUnit7   StorageUnits formatAsBinaryUnit input1  format   String formattedUnit8   StorageUnits formatAsBinaryUnit input2  format    Assert assertEquals  1 kB   formattedUnit1   Assert assertEquals  1 MB   formattedUnit2   Assert assertEquals  1 00 KiB   formattedUnit3   Assert assertEquals  1 00 MiB   formattedUnit4   Assert assertEquals  1 02 kB   formattedUnit5   Assert assertEquals  1 05 MB   formattedUnit6   Assert assertEquals  1 KiB   formattedUnit7   Assert assertEquals  1 MiB   formattedUnit8     In case you want to force a certain unit  do this   String formattedUnit9   StorageUnits formatAsKibibyte input2   String formattedUnit10   StorageUnits formatAsCommonMegabyte input2    Assert assertEquals  1024 00 KiB   formattedUnit9   Assert assertEquals  1 00 MB   formattedUnit10

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I usually do it in this way  what do you think  public static String getFileSize double size        return  getFileSize size 0 1024      public static String  getFileSize double size  int i  double base        String units    quot  KMGTP quot       String unit    i gt 0    quot  quot  units charAt i   toUpperCase    quot i quot   quot  quot       if size lt base          return size   quot   quot  unit trim    quot B quot       else           size   Math floor size base           return  getFileSize size   i base

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Create an interface  public interface IUnits       public String format long size  String pattern       public long getUnitSize       Create the StorageUnits class  import java text DecimalFormat   public class StorageUnits        private static final long K   1024      private static final long M   K   K      private static final long G   M   K      private static final long T   G   K       enum Unit implements IUnits            TERA BYTE                Override             public String format long size  String pattern                    return format size  getUnitSize     quot TB quot   pattern                              Override             public long getUnitSize                     return T                             Override             public String toString                     return  quot Terabytes quot                                    GIGA BYTE                Override             public String format long size  String pattern                    return format size  getUnitSize     quot GB quot   pattern                              Override             public long getUnitSize                     return G                             Override             public String toString                     return  quot Gigabytes quot                                    MEGA BYTE                Override             public String format long size  String pattern                    return format size  getUnitSize     quot MB quot   pattern                              Override             public long getUnitSize                     return M                             Override             public String toString                     return  quot Megabytes quot                                    KILO BYTE                Override             public String format long size  String pattern                    return format size  getUnitSize     quot kB quot   pattern                              Override             public long getUnitSize                     return K                             Override             public String toString                     return  quot Kilobytes quot                                      String format long size  long base  String unit  String pattern                return new DecimalFormat pattern  format                             Long valueOf size  doubleValue                                Long valueOf base  doubleValue                   unit                       public static String format long size  String pattern            for Unit unit   Unit values                  if size  gt   unit getUnitSize                      return unit format size  pattern                                   return   quot      quot    size    quot      quot               public static String format long size            return format size   quot     0   quot             Call it  class Main       public static void main String    args            System out println StorageUnits format 21885            System out println StorageUnits format 2188121545L             Output  21 4kB 2GB

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I asked the same question recently  Format file size as MB  GB  etc  While there is no out-of-the-box answer  I can live with the solution  private static final long K   1024  private static final long M   K   K  private static final long G   M   K  private static final long T   G   K   public static String convertToStringRepresentation final long value       final long   dividers   new long     T  G  M  K  1        final String   units   new String      quot TB quot    quot GB quot    quot MB quot    quot KB quot    quot B quot         if value  lt  1          throw new IllegalArgumentException  quot Invalid file size   quot    value       String result   null      for int i   0  i  lt  dividers length  i             final long divider   dividers i           if value  gt   divider               result   format value  divider  units i                break                      return result     private static String format final long value      final long divider      final String unit       final double result           divider  gt  1    double  value    double  divider    double  value      return new DecimalFormat  quot     0   quot   format result     quot   quot    unit     Test code  public static void main final String   args       final long   l   new long     1l  4343l  43434334l  3563543743l        for final long ll   l           System out println convertToStringRepresentation ll             Output  on my German locale   1 B 4 2 KB 41 4 MB 3 3 GB   I have opened an issue requesting this functionality for Google Guava  Perhaps someone would care to support it

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private static final String   Q   new String        K    M    G    T    P    E     public String getAsString long bytes        for  int i   6  i   0  i--                double step   Math pow 1024  i           if  bytes   step  return String format   3 1f  s   bytes   step  Q i              return Long toString bytes

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FileUtils byteCountToDisplaySize long size  would work if your project can depend on org apache commons io   JavaDoc for this method

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org springframework util unit DataSize could suit this requirement at least for the calculation  Then a simple decorator will do

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String   fileSizeUnits     quot bytes quot    quot KB quot    quot MB quot    quot GB quot    quot TB quot    quot PB quot    quot EB quot    quot ZB quot    quot YB quot     public String calculateProperFileSize double bytes       String sizeToReturn    quot  quot       int index   0      for index   0  index  lt  fileSizeUnits length  index             if bytes  lt  1024               break                    bytes   bytes   1024             System out println  quot File size in proper format   quot    bytes    quot   quot    fileSizeUnits index        sizeToReturn   String valueOf bytes     quot   quot    fileSizeUnits index       return sizeToReturn     Just add more file units  if any missing   and you will see unit size up to that unit  if your file has that much length

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I m using slighly modified method than accepted answer   public static String formatFileSize long bytes            if  bytes  lt   0  return  quot  quot           if  bytes  lt  1000  return bytes    quot  B quot           CharacterIterator ci   new StringCharacterIterator  quot kMGTPE quot            while  bytes  gt   99 999                bytes    1000              ci next                      return String format Locale getDefault     quot   1f  cB quot   bytes   1000 0  ci current            Because i want to see another output                                 SI                        0              lt --------- instead of 0 B                   27        27 B                       999       999 B                    1000      1 0 kB                    1023      1 0 kB                    1024      1 0 kB                  1728      1 7 kB                  110592      0 1 MB  lt --------- instead of 110 6 kB              7077888      7 1 MB              452984832      0 5 GB  lt --------- instead of 453 0 MB          28991029248     29 0 GB

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Here s the C   NET equivalent for Java correct consensus answer above  there s another below which has shorter code       public static String BytesNumberToHumanReadableString long bytes  bool SI1000orBinary1024                int unit   SI1000orBinary1024   1000   1024          if  bytes  lt  unit              return bytes    quot  B quot            int exp    int  Math Log bytes    Math Log unit            String pre    SI1000orBinary1024    quot kMGTPE quot     quot KMGTPE quot    exp - 1      SI1000orBinary1024    quot  quot     quot i quot            return String Format  quot  0 F1   1 B quot   bytes   Math Pow unit  exp   pre          Technically speaking  if we stick to SI units  this routine works for any regular use of numbers  There are many other good answers from experts  Suppose you are doing databinding of numbers on gridviews  it s worth to check out performance optimized routines from them  PS  This was posted because this question answer came up on top on a Google search while I was doing a C  project

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public static String floatForm  double d               return new DecimalFormat         format d               public static String bytesToHuman  long size                long Kb   1    1024          long Mb   Kb   1024          long Gb   Mb   1024          long Tb   Gb   1024          long Pb   Tb   1024          long Eb   Pb   1024           if  size  lt   Kb                  return floatForm         size           byte           if  size  gt   Kb  amp  amp  size  lt  Mb     return floatForm  double size   Kb      Kb           if  size  gt   Mb  amp  amp  size  lt  Gb     return floatForm  double size   Mb      Mb           if  size  gt   Gb  amp  amp  size  lt  Tb     return floatForm  double size   Gb      Gb           if  size  gt   Tb  amp  amp  size  lt  Pb     return floatForm  double size   Tb      Tb           if  size  gt   Pb  amp  amp  size  lt  Eb     return floatForm  double size   Pb      Pb           if  size  gt   Eb                  return floatForm  double size   Eb      Eb            return

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public String humanReadable long size        long limit   10   1024      long limit2   limit   2 - 1      String negative           if size  lt  0            negative    -           size   Math abs size              if size  lt  limit            return String format   s s bytes   negative  size         else           size   Math round  double  size   1024           if  size  lt  limit2                return String format   s s kB   negative  size             else               size   Math round  double size   1024               if  size  lt  limit2                    return String format   s s MB   negative  size                 else                   size   Math round  double size   1024                   if  size  lt  limit2                        return String format   s s GB   negative  size                     else                       size   Math round  double size   1024                           return String format   s s TB   negative  size

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private String bytesIntoHumanReadable long bytes        long kilobyte   1024      long megabyte   kilobyte   1024      long gigabyte   megabyte   1024      long terabyte   gigabyte   1024       if   bytes  gt   0   amp  amp   bytes  lt  kilobyte             return bytes    quot  B quot          else if   bytes  gt   kilobyte   amp  amp   bytes  lt  megabyte             return  bytes   kilobyte     quot  KB quot          else if   bytes  gt   megabyte   amp  amp   bytes  lt  gigabyte             return  bytes   megabyte     quot  MB quot          else if   bytes  gt   gigabyte   amp  amp   bytes  lt  terabyte             return  bytes   gigabyte     quot  GB quot          else if  bytes  gt   terabyte            return  bytes   terabyte     quot  TB quot          else           return bytes    quot  Bytes quot

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Here is the conversion from aioobe converted to Kotlin         https   stackoverflow com a 3758880 1006741     fun Long humanReadableByteCountBinary    String       val b   when  this            Long MIN VALUE - gt  Long MAX VALUE         else - gt  abs this            return when           b  lt  1024L - gt   quot  this B quot          b  lt   0xfffccccccccccccL shr 40 - gt   quot   1f KiB quot  format Locale UK  this   1024 0          b  lt   0xfffccccccccccccL shr 30 - gt   quot   1f MiB quot  format Locale UK  this   1048576 0          b  lt   0xfffccccccccccccL shr 20 - gt   quot   1f GiB quot  format Locale UK  this   1 073741824E9          b  lt   0xfffccccccccccccL shr 10 - gt   quot   1f TiB quot  format Locale UK  this   1 099511627776E12          b  lt   0xfffccccccccccccL - gt   quot   1f PiB quot  format Locale UK   this shr 10    1 099511627776E12          else - gt   quot   1f EiB quot  format Locale UK   this shr 20    1 099511627776E12

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Kotlin Version via Extension Property If you are using kotlin  it s pretty easy to format file size by these extension properties  It is loop-free and completely based on pure math   HumanizeUtils kt import java io File import kotlin math log2 import kotlin math pow          author aminography      val File formatSize  String     get     length   formatAsFileSize  val Int formatAsFileSize  String     get     toLong   formatAsFileSize  val Long formatAsFileSize  String     get     log2 if  this    0L  toDouble   else 1 0  toInt   div 10  let           val precision   when  it                0 - gt  0  1 - gt  1  else - gt  2                   val prefix   arrayOf  quot  quot    quot K quot    quot M quot    quot G quot    quot T quot    quot P quot    quot E quot    quot Z quot    quot Y quot           String format  quot     precision f   prefix it  B quot   toDouble     2 0 pow it   10 0           Usage  println  quot 0            quot    0 formatAsFileSize  println  quot 170          quot    170 formatAsFileSize  println  quot 14356        quot    14356 formatAsFileSize  println  quot 968542985    quot    968542985 formatAsFileSize  println  quot 8729842496   quot    8729842496 formatAsFileSize   println  quot file   quot    file formatSize    Result  0           0 B 170         170 B 14356       14 0 KB 968542985   923 67 MB 8729842496  8 13 GB  file  6 15 MB

[java] How can I convert byte size into a human-readable format in Java?

SI (1 k = 1,000)

Binary (1 Ki = 1,024)

Example output:

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