Java File Size Get fileSizeString(long bytes)

Description

file Size String

License

Open Source License

Declaration

public static String fileSizeString(long bytes) 

Method Source Code

//package com.java2s;
/*/*w w w .  j  a v  a 2s  .co  m*/
 * $Id: StringUtils.java,v 1.3 2008-01-30 14:07:48 kashif Exp $
 *
 * Copyright (C) 2002,2003  by Brockmann Consult (info@brockmann-consult.de)
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation. This program is distributed in the hope it will
 * be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 */

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

public class Main {
    private static final double ONE_KB = 1024.0;
    private static final double ONE_MB = 1024.0 * 1024.0;
    private static final double ONE_GB = 1024.0 * 1024.0 * 1024.0;
    private static DecimalFormat format;

    public static String fileSizeString(long bytes) {
        ensureFormat();
        final StringBuffer result = new StringBuffer(64);
        double value;

        if (bytes >= ONE_GB) {
            value = scaleToThreeDecimals(bytes, ONE_GB);
            result.append(format.format(value));
            result.append(" GB");
        } else if (bytes >= ONE_MB) {
            value = scaleToThreeDecimals(bytes, ONE_MB);
            result.append(format.format(value));
            result.append(" MB");
        } else {
            value = scaleToThreeDecimals(bytes, ONE_KB);
            result.append(format.format(value));
            result.append(" KB");
        }

        return result.toString();
    }

    private static void ensureFormat() {
        if (format == null) {
            format = new DecimalFormat("0.0");
            format.setMaximumFractionDigits(3);
            format.setDecimalSeparatorAlwaysShown(true);
            final DecimalFormatSymbols symbols = new DecimalFormatSymbols();
            symbols.setDecimalSeparator('.');
            format.setDecimalFormatSymbols(symbols);
        }
    }

    private static double scaleToThreeDecimals(double value, double scale) {
        double upScaled = (1000.0 * value / scale);
        int truncated = (int) (upScaled + 0.5);
        return truncated * 0.001;
    }
}

Related

1. countFileDisplaySize(long size)
2. countFileSize(String pathname)
3. getFileKBSize(long fsize)
4. getFileSize(@Nonnull File file)
5. getFileSize(File dir)
6. getFileSize(File element)