BufferedWriter to write at BufferedReader position

Question

My code reads through an xml file encoded with UTF-8 until a specfied string has been found. It finds the specified string fine, but I wish to write at this point in the file.

I would much prefer to do this through a stream as only small tasks need to be done.

I cannot find a way to do this. Any alternative methods are welcome.

Code so far:

final String RESOURCE = "/path/to/file.xml";

BufferedReader in = new BufferedReader(new InputStreamReader(ClassLoader.class.getResourceAsStream(RESOURCE), "UTF-8"));
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(ClassLoader.class.getResource(RESOURCE).getPath()),"UTF-8"));

String fileLine = in.readLine();

while (!fileLine.contains("some string")) {

    fileLine = in.readLine();

}

// File writing code here

Answer 1

You can't really write into the middle of the file, except for overwriting existing bytes (using something like RandomAccessFile). that would only work, however, if what you needed to write was exactly the same byte length as what you were replacing, which i highly doubt.

instead, you need to re-write the file to a new file, copying the input to the output, replacing the parts you need to replace in the process. there are a variety of ways you could do this. i would recommend using a StAX event reader and writer as the StAX api is fairly user friendly (compared to SAX) as well as fast and memory efficient.