How to list a 2 million files directory in java without having an “out of memory” exception

Question

I have to deal with a directory of about 2 million xml\'s to be processed.

I\'ve already solved the processing distributing the work between machines and threads us

Answer 1

If Java 7 is not an option, this hack will work (for UNIX):

Process process = Runtime.getRuntime().exec(new String[]{"ls", "-f", "/path"});
BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
String line;
while (null != (line = reader.readLine())) {
    if (line.startsWith("."))
        continue;
    System.out.println(line);
}

The -f parameter will speed it up (from man ls):

-f     do not sort, enable -aU, disable -lst