Same as Before

A dump of the new file is indistinguishable from that of the previous file. A program that reads data from this file must be written with the knowledge of how the file was written. (Of course, since I know how it was written the brackets under the bytes show the intended groupings).

Here is an excerpt from the DataOutputStream documentation.

public void writeBytes(String s) throws IOException
    Writes the low eight bits of each character in the string.

This does not write the String object to the stream, but writes bytes based on the characters held in the String. A String object (like all objects) is a discrete entity with its own data, methods, and internal organization. The writeBytes() just writes out the characters. If the characters in a String are from the usual Western alphabet, the writeBytes() method writes normal 8-bit ASCII.