Format file size as MB, GB, etc [duplicate]

public static String readableFileSize(long size) {
    if(size <= 0) return "0";
    final String[] units = new String[] { "B", "kB", "MB", "GB", "TB" };
    int digitGroups = (int) (Math.log10(size)/Math.log10(1024));
    return new DecimalFormat("#,##0.#").format(size/Math.pow(1024, digitGroups)) + " " + units[digitGroups];
}

This will work up to 1000 TB.... and the program is short!

You'll probably have more luck with java.text.DecimalFormat. This code should probably do it (just winging it though...)

new DecimalFormat("#,##0.#").format(value) + " " + unit

It is surprising for me, but a loop-based algorithm is about 10% faster.

public static String toNumInUnits(long bytes) {
    int u = 0;
    for ( ; bytes > 1024*1024; bytes >>= 10) {
        u++;
    }
    if (bytes > 1024)
        u++;
    return String.format("%.1f %cB", bytes/1024f, " kMGTPE".charAt(u));
}