Class FileEnumerator

java.lang.Object
org.javagi.base.ProxyInstance
org.gnome.gobject.TypeInstance
org.gnome.gobject.GObject
org.gnome.gio.FileEnumerator
All Implemented Interfaces:
Proxy
@Generated("org.javagi.JavaGI") public class FileEnumerator extends GObject

GFileEnumerator allows you to operate on a set of File objects, returning a FileInfo structure for each file enumerated (e.g. File.enumerateChildren(String, Set, Cancellable) will return a GFileEnumerator for each of the children within a directory).

To get the next file's information from a GFileEnumerator, use nextFile(Cancellable) or its asynchronous version, nextFilesAsync(int, int, Cancellable, AsyncReadyCallback). Note that the asynchronous version will return a list of FileInfo objects, whereas the synchronous will only return the next file in the enumerator.

The ordering of returned files is unspecified for non-Unix platforms; for more information, see Dir#readName. On Unix, when operating on local files, returned files will be sorted by inode number. Effectively you can assume that the ordering of returned files will be stable between successive calls (and applications) assuming the directory is unchanged.

If your application needs a specific ordering, such as by name or modification time, you will have to implement that in your application code.

To close a GFileEnumerator, use close(Cancellable), or its asynchronous version, closeAsync(int, Cancellable, AsyncReadyCallback). Once a GFileEnumerator is closed, no further actions may be performed on it, and it should be freed with GObject#unref.

  • Constructor Details

    • FileEnumerator

      public FileEnumerator(MemorySegment address)
      Create a FileEnumerator instance for the provided memory address.
      Parameters:
      address - the memory address of the native object

    • FileEnumerator

      public FileEnumerator()
      Create a new FileEnumerator.

  • Method Details

    • getType

      public static @Nullable Type getType()
      Get the GType of the FileEnumerator class.
      Returns:
      the GType

    • getMemoryLayout

      public static MemoryLayout getMemoryLayout()
      The memory layout of the native struct.
      Returns:
      the memory layout

    • asParent

      protected FileEnumerator asParent()
      Return this instance as if it were its parent type. Comparable to the Java super keyword, but ensures the parent typeclass is also used in native code.
      Overrides:
      asParent in class GObject
      Returns:
      the instance as if it were its parent type

    • close

      public boolean close(@Nullable Cancellable cancellable) throws GErrorException

      Releases all resources used by this enumerator, making the enumerator return IOErrorEnum.CLOSED on all calls.

      This will be automatically called when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.

      Parameters:
      cancellable - optional GCancellable object, null to ignore.
      Returns:
      TRUE on success or FALSE on error.
      Throws:
      GErrorException - see GError

    • closeAsync

      public void closeAsync(int ioPriority, @Nullable Cancellable cancellable, @Nullable AsyncReadyCallback callback)

      Asynchronously closes the file enumerator.

      If cancellable is not null, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error IOErrorEnum.CANCELLED will be returned in g_file_enumerator_close_finish().

      Parameters:
      ioPriority - the I/O priority of the request
      cancellable - optional GCancellable object, null to ignore.
      callback - a GAsyncReadyCallback to call when the request is satisfied

    • closeFinish

      public boolean closeFinish(AsyncResult result) throws GErrorException

      Finishes closing a file enumerator, started from g_file_enumerator_close_async().

      If the file enumerator was already closed when g_file_enumerator_close_async() was called, then this function will report IOErrorEnum.CLOSED in error, and return false. If the file enumerator had pending operation when the close operation was started, then this function will report IOErrorEnum.PENDING, and return false. If cancellable was not null, then the operation may have been cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error IOErrorEnum.CANCELLED will be set, and false will be returned.

      Parameters:
      result - a GAsyncResult.
      Returns:
      true if the close operation has finished successfully.
      Throws:
      GErrorException - see GError

    • getChild

      public File getChild(FileInfo info)

      Return a new GFile which refers to the file named by info in the source directory of enumerator. This function is primarily intended to be used inside loops with g_file_enumerator_next_file().

      To use this, G_FILE_ATTRIBUTE_STANDARD_NAME must have been listed in the attributes list used when creating the GFileEnumerator.

      This is a convenience method that's equivalent to:

        gchar *name = g_file_info_get_name (info);
  GFile *child = g_file_get_child (g_file_enumerator_get_container (enumr),
                                   name);
      Parameters:
      info - a GFileInfo gotten from g_file_enumerator_next_file() or the async equivalents.
      Returns:
      a GFile for the GFileInfo passed it.
      Since:
      2.36

    • getContainer

      public File getContainer()
      Get the GFile container which is being enumerated.
      Returns:
      the GFile which is being enumerated.
      Since:
      2.18

    • hasPending

      public boolean hasPending()
      Checks if the file enumerator has pending operations.
      Returns:
      true if the this FileEnumerator has pending operations.

    • isClosed

      public boolean isClosed()
      Checks if the file enumerator has been closed.
      Returns:
      true if the this FileEnumerator is closed.

    • iterate

      public boolean iterate(@Nullable Out<FileInfo> outInfo, @Nullable Out<File> outChild, @Nullable Cancellable cancellable) throws GErrorException

      This is a version of g_file_enumerator_next_file() that's easier to use correctly from C programs. With g_file_enumerator_next_file(), the gboolean return value signifies "end of iteration or error", which requires allocation of a temporary GError.

      In contrast, with this function, a false return from g_file_enumerator_iterate() always means "error". End of iteration is signaled by outInfo or outChild being null.

      Another crucial difference is that the references for outInfo and outChild are owned by this FileEnumerator (they are cached as hidden properties). You must not unref them in your own code. This makes memory management significantly easier for C code in combination with loops.

      Finally, this function optionally allows retrieving a GFile as well.

      You must specify at least one of outInfo or outChild.

      The code pattern for correctly using g_file_enumerator_iterate() from C is:

      direnum = g_file_enumerate_children (file, ...);
while (TRUE)
  {
    GFileInfo *info;
    if (!g_file_enumerator_iterate (direnum, &info, NULL, cancellable, error))
      goto out;
    if (!info)
      break;
    ... do stuff with "info"; do not unref it! ...
  }

out:
  g_object_unref (direnum); // Note: frees the last @info
      Parameters:
      outInfo - Output location for the next GFileInfo, or null
      outChild - Output location for the next GFile, or null
      cancellable - a GCancellable
      Throws:
      GErrorException - see GError
      Since:
      2.44

    • nextFile

      public @Nullable FileInfo nextFile(@Nullable Cancellable cancellable) throws GErrorException

      Returns information for the next file in the enumerated object. Will block until the information is available. The GFileInfo returned from this function will contain attributes that match the attribute string that was passed when the GFileEnumerator was created.

      See the documentation of GFileEnumerator for information about the order of returned files.

      On error, returns null and sets error to the error. If the enumerator is at the end, null will be returned and error will be unset.

      Parameters:
      cancellable - optional GCancellable object, null to ignore.
      Returns:
      A GFileInfo or null on error or end of enumerator. Free the returned object with g_object_unref() when no longer needed.
      Throws:
      GErrorException - see GError

    • nextFilesAsync

      public void nextFilesAsync(int numFiles, int ioPriority, @Nullable Cancellable cancellable, @Nullable AsyncReadyCallback callback)

      Request information for a number of files from the enumerator asynchronously. When all I/O for the operation is finished the callback will be called with the requested information.

      See the documentation of GFileEnumerator for information about the order of returned files.

      Once the end of the enumerator is reached, or if an error occurs, the callback will be called with an empty list. In this case, the previous call to g_file_enumerator_next_files_async() will typically have returned fewer than numFiles items.

      If a request is cancelled the callback will be called with IOErrorEnum.CANCELLED.

      This leads to the following pseudo-code usage:

      g_autoptr(GFile) dir = get_directory ();
g_autoptr(GFileEnumerator) enumerator = NULL;
g_autolist(GFileInfo) files = NULL;
g_autoptr(GError) local_error = NULL;

enumerator = yield g_file_enumerate_children_async (dir,
                                                    G_FILE_ATTRIBUTE_STANDARD_NAME ","
                                                    G_FILE_ATTRIBUTE_STANDARD_TYPE,
                                                    G_FILE_QUERY_INFO_NONE,
                                                    G_PRIORITY_DEFAULT,
                                                    cancellable,
                                                    …,
                                                    &local_error);
if (enumerator == NULL)
  g_error ("Error enumerating: %s", local_error->message);

// Loop until no files are returned, either because the end of the enumerator
// has been reached, or an error was returned.
do
  {
    files = yield g_file_enumerator_next_files_async (enumerator,
                                                      5,  // number of files to request
                                                      G_PRIORITY_DEFAULT,
                                                      cancellable,
                                                      …,
                                                      &local_error);

    // Process the returned files, but don’t assume that exactly 5 were returned.
    for (GList *l = files; l != NULL; l = l->next)
      {
        GFileInfo *info = l->data;
        handle_file_info (info);
      }
  }
while (files != NULL);

if (local_error != NULL &&
    !g_error_matches (local_error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
  g_error ("Error while enumerating: %s", local_error->message);

      During an async request no other sync and async calls are allowed, and will result in IOErrorEnum.PENDING errors.

      Any outstanding I/O request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is G_PRIORITY_DEFAULT.

      Parameters:
      numFiles - the number of file info objects to request
      ioPriority - the I/O priority of the request
      cancellable - optional GCancellable object, null to ignore.
      callback - a GAsyncReadyCallback to call when the request is satisfied

    • nextFilesFinish

      public List<FileInfo> nextFilesFinish(AsyncResult result) throws GErrorException
      Finishes the asynchronous operation started with g_file_enumerator_next_files_async().
      Parameters:
      result - a GAsyncResult.
      Returns:
      a GList of GFileInfos. You must free the list with g_list_free() and unref the infos with g_object_unref() when you're done with them.
      Throws:
      GErrorException - see GError

    • setPending

      public void setPending(boolean pending)
      Sets the file enumerator as having pending operations.
      Parameters:
      pending - a boolean value.

    • closeFn

      protected boolean closeFn(@Nullable Cancellable cancellable) throws GErrorException
      Throws:
      GErrorException

    • builder

      public static FileEnumerator.Builder<? extends FileEnumerator.Builder> builder()
      A FileEnumerator.Builder object constructs a FileEnumerator with the specified properties. Use the various set...() methods to set properties, and finish construction with FileEnumerator.Builder.build().
      Returns:
      the builder object