Read portions of bytes to byte array and store them in new files when buffer is full or it is end of file

FileSplit.java

class FileSplit {
    public static void splitFile(File f) throws IOException {
        int partCounter = 1;//I like to name parts from 001, 002, 003, ...
                            //you can change it to 0 if you want 000, 001, ...

        int sizeOfFiles = 1024 * 1024;// 1MB
        byte[] buffer = new byte[sizeOfFiles];

        try (BufferedInputStream bis = new BufferedInputStream(
                new FileInputStream(f))) {//try-with-resources to ensure closing stream
            String name = f.getName();

            int tmp = 0;
            while ((tmp = bis.read(buffer)) > 0) {
                //write each chunk of data into separate file with different number in name
                File newFile = new File(f.getParent(), name + "."
                        + String.format("%03d", partCounter++));
                try (FileOutputStream out = new FileOutputStream(newFile)) {
                    out.write(buffer, 0, tmp);//tmp is chunk size
                }
            }
        }
    }

    public static void main(String[] args) throws IOException {
        splitFile(new File("D:\\destination\\myFile.mp3"));
    }
}

public static void mergeFiles(List<File> files, File into)
        throws IOException {
    try (BufferedOutputStream mergingStream = new BufferedOutputStream(
            new FileOutputStream(into))) {
        for (File f : files) {
            Files.copy(f.toPath(), mergingStream);
        }
    }
}