e032. listing the file system roots.txt

这里面包含了一百多个JAVA源文件

UNIX file systems have a single root, `/'. On Windows, each drive is a root. For example the C drive is represented by the root C:\. 
    File[] roots = File.listRoots();
    for (int i=0; i<roots.length; i++) {
        process(roots[i]);
    }