Display usage of all volumes or the specified one

VolumeUsage.java

package com.arcvideo.berd.face.utils;
/*
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 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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import java.io.IOException;
import java.nio.file.FileStore;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Paths;

/**
 * Example utility that works like the df(1M) program to print out disk space
 * information
 */

public class VolumeUsage {

  static final long K = 1024;

  static void printFileStore(FileStore store) throws IOException {
    long total = store.getTotalSpace() / K;
    long used = (store.getTotalSpace() - store.getUnallocatedSpace()) / K;
    long avail = store.getUsableSpace() / K;

    String s = store.toString();
    if (s.length() > 20) {
      System.out.println(s);
      s = "";
    }
    System.out.format("%-20s %12d %12d %12d\n", s, total, used, avail);
  }

  public static void main(String[] args) throws IOException {
    System.out.format("%-20s %12s %12s %12s\n", "Filesystem", "kbytes", "used", "avail");
    if (args.length == 0) {
      FileSystem fs = FileSystems.getDefault();
      for (FileStore store: fs.getFileStores()) {
        printFileStore(store);
      }
    } else {
      for (String file: args) {
        FileStore store = Files.getFileStore(Paths.get(file));
        printFileStore(store);
      }
    }
  }

}