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 "1 Kb" and 1024*1024 should become "1 Mb".

I am kind of sick of writing this utility method for each project. Is there a static method in Apache Commons for this?

Answer 1

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 < bytes && bytes < 1000) {         return bytes + " B";     }     CharacterIterator ci = new StringCharacterIterator("kMGTPE");     while (bytes <= -999_950 || bytes >= 999_950) {         bytes /= 1000;         ci.next();     }     return String.format("%.1f %cB", 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 < 1024) {         return bytes + " B";     }     long value = absB;     CharacterIterator ci = new StringCharacterIterator("KMGTPE");     for (int i = 40; i >= 0 && absB > 0xfffccccccccccccL >> i; i -= 10) {         value >>= 10;         ci.next();     }     value *= Long.signum(bytes);     return String.format("%.1f %ciB", 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) 

Answer 2

FileUtils.byteCountToDisplaySize(long size) would work if your project can depend on org.apache.commons.io.

JavaDoc for this method