May 202016

ADM

How to convert byte size into human readable format in java

  • 20 May 2016
  • ADM

 

 

 

How to convert byte size into human readable format in java - images/logos/java.jpg

 

When you need to display informations about files or disk free/used space is useful to convert the bytes size in a human readable format.

Conversion table
Name Symbol Binary Number of bytes Equal to
Kilobyte KB 210 1,024 1024 B
Megabyte MB 220 1,048,576 1024 KB
Gigabyte GB 230 1,073,741,824 1024 MB
Terabyte TB 240 1,099,511,627,776 1024 GB
Petabyte PB 250 1,125,899,906,842,624 1024 TB
Exabyte EB 260 1,152,921,504,606,846,976 1024 PB
Zettabyte ZB 270 1,180,591,620,717,411,303,424 1024 EB
Yottabyte YB 280 1,208,925,819,614,629,174,706,176 1024 ZB

Example

Here is a simple Java method to convert bytes in human readable format.

package com.admfactory.io;

public class ByteSizeHumanReadable {

    /**
     * Method to format bytes in human readable format
     * 
     * @param bytes
     *            - the value in bytes
     * @param digits
     *            - number of decimals to be displayed
     * @return human readable format string
     */
    public static String format(double bytes, int digits) {
        String[] dictionary = { "bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
        int index = 0;
        for (index = 0; index < dictionary.length; index++) {
            if (bytes < 1024) {
                break;
            }
            bytes = bytes / 1024;
        }
        return String.format("%." + digits + "f", bytes) + " " + dictionary[index];
    }

    public static void main(String[] args) {
        long n1 = 12345678L;
        long n2 = 98745678245L;
        long n3 = Long.MAX_VALUE;
        System.out.println("Test byte human reabable format");
        System.out.println();
        System.out.println("n1: " + n1 + " ==> 2 decimals: " + format(n1, 2));
        System.out.println("n1: " + n1 + " ==> 3 decimals: " + format(n1, 3));
        System.out.println();
        System.out.println("n2: " + n2 + " ==> 2 decimals: " + format(n2, 2));
        System.out.println("n2: " + n2 + " ==> 3 decimals: " + format(n2, 3));
        System.out.println();
        System.out.println("n3: " + n2 + " ==> 2 decimals: " + format(n3, 2));
        System.out.println("n3: " + n2 + " ==> 3 decimals: " + format(n3, 3));
    }
}

Output

Test byte human reabable format

n1: 12345678 ==> 2 decimals: 11.77 MB
n1: 12345678 ==> 3 decimals: 11.774 MB

n2: 98745678245 ==> 2 decimals: 91.96 GB
n2: 98745678245 ==> 3 decimals: 91.964 GB

n3: 98745678245 ==> 2 decimals: 8.00 EB
n3: 98745678245 ==> 3 decimals: 8.000 EB