Code missing closing parenthesis. Errant continue statement.

[authentictech]

In Learn > The Java I/O API > File System Basics > Managing File Attributes, section "Determining MIME Type", there is a missing closing parenthesis:

try {
 String type = Files.probeContentType(filename);
 if (type == null) {
 System.err.format("'%s' has an" + " unknown filetype.%n", filename);
 } else if (!type.equals("text/plain") { // <-- parenthesis missing here
 System.err.format("'%s' is not" + " a plain text file.%n", filename);
 continue;
 }
} catch (IOException x) {
 System.err.println(x);
}

I also get a compiler error about the continue statement: "error: continue outside of loop". (I presume the code was copied originally from a loop.)

[willy-b]

Great catch!

Re: why they have a "continue" there -- it looks possibly copied from the more complete looping code example they provided later in the tutorial at https://dev.java/learn/java-io/file-system/watching-dir-changes/#processing-events (archived as is at https://web.archive.org/web/20260710052409/https://dev.java/learn/java-io/file-system/watching-dir-changes/#processing-events )

[... run the setup in earlier paragraphs by the dev.java team, to obtain `watcher` and register a directory with the watcher...]
// wait for key to be signaled
WatchKey key;
try {
 key = watcher.take();
} catch (InterruptedException x) {
 return; // [not valid in JShell but would be valid in an enclosing method]
}
// [...]
for (WatchEvent<?> event: key.pollEvents()) {
 WatchEvent.Kind<?> kind = event.kind();

 // This key is registered only
 // for ENTRY_CREATE events,
 // but an OVERFLOW event can
 // occur regardless if events
 // are lost or discarded.
 if (kind == OVERFLOW) {
 continue;
 }

 // The filename is the
 // context of the event.
 WatchEvent<Path> ev = (WatchEvent<Path>)event;
 Path filename = ev.context();

 // Verify that the new
 // file is a text file.
 try {
 // Resolve the filename against the directory.
 // If the filename is "test" and the directory is "foo",
 // the resolved name is "test/foo".
 Path child = dir.resolve(filename);
 if (!Files.probeContentType(child).equals("text/plain")) { // [btw this is unsafe for NPEs: this should be `if (!"text/plain".equals(Files.probeContentType(child)))` to avoid a NPE]
 System.err.format("New file '%s'" +
 " is not a plain text file.%n", filename);
 continue;
 }
 } catch (IOException x) {
 System.err.println(x);
 continue;
 }

 // Email the file to the
 // specified email alias.
 System.out.format("Emailing file %s%n", filename);
 //Details left to reader....
}
// [...]

I agree without the context of their later example it is confusing and that the continue should probably not be shown in the simplified pseudocode shown on https://dev.java/learn/java-io/file-system/metadata/#mime-type .

BTW, on the other page this example appears copied from https://web.archive.org/web/20260710052409/https://dev.java/learn/java-io/file-system/watching-dir-changes/#processing-events (archived as is at https://web.archive.org/web/20260710052409/https://dev.java/learn/java-io/file-system/watching-dir-changes/#processing-events )

• The line

  if (!Files.probeContentType(child).equals("text/plain")) {
  

  should be

  if (!"text/plain".equals(Files.probeContentType(child))) {
  

  to avoid a possible NullPointerException if probeContentType returns null which is not caught in a separate condition on that page unlike the page you cited (note I did not add/edit the line I am reporting is unsafe; see e.g. the archived version from 2025: https://web.archive.org/web/20250616164901/https://dev.java/learn/java-io/file-system/watching-dir-changes/#processing-events#processing-events ).

---

Also, just noting as I reported some errors on these pages earlier that
the particular code example you are reporting here on https://dev.java/learn/java-io/file-system/metadata/#mime-type was NOT updated by me NOR the dev.java team as part of recommendations I made in a ticket on that series of articles ( #210 (comment) ) or otherwise, though it sounds similar to material discussed there and occurs close to items I reported bugs in within that ticket.

The error you report here was present from at least 2025 already: https://web.archive.org/web/20251012140905/https://dev.java/learn/java-io/file-system/metadata/ .

---

Thanks!

[JosePaumard]

Thanks to both of your for this report! A fix is on its way.
As for the comment #210, I see that you closed it, does your comment on this one mean that there are in fact elements that should be fixed and that were not?
Thank you again!