/**
* Make a path relative with respect to a root path. absPath is always assumed to descend from
* root. Otherwise returned path is null.
*/
static String makeRelative(Path root, Path absPath) {
if (!absPath.isAbsolute()) {
throw new IllegalArgumentException("!absPath.isAbsolute(), absPath=" + absPath);
}
String p = absPath.toUri().getPath();
StringTokenizer pathTokens = new StringTokenizer(p, "/");
for (StringTokenizer rootTokens = new StringTokenizer(root.toUri().getPath(), "/");
rootTokens.hasMoreTokens(); ) {
if (!rootTokens.nextToken().equals(pathTokens.nextToken())) {
return null;
}
}
StringBuilder sb = new StringBuilder();
for (; pathTokens.hasMoreTokens(); ) {
sb.append(pathTokens.nextToken());
if (pathTokens.hasMoreTokens()) {
sb.append(Path.SEPARATOR);
}
}
return sb.length() == 0 ? "." : sb.toString();
}
