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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QAbstractFileEngineIterator
public abstract class QAbstractFileEngineIterator
The QAbstractFileEngineIterator
class provides an iterator interface for custom file engines. If all you want is to iterate over entries in a directory, see QDirIterator
instead. This class is only for custom file engine authors.
QAbstractFileEngineIterator
is a unidirectional single-use virtual iterator that plugs into QDirIterator
, providing transparent proxy iteration for custom file engines.
You can subclass QAbstractFileEngineIterator
to provide an iterator when writing your own file engine. To plug the iterator into your file system, you simply return an instance of this subclass from a reimplementation of QAbstractFileEngine::beginEntryList().
Example:
class CustomFileEngine extends QAbstractFileEngine { QAbstractFileEngineIterator beginEntryList(QDir.Filters filters, java.util.List<String> nameFilters) { return new CustomFileEngineIterator(filters, nameFilters); } //... }
QAbstractFileEngineIterator
is associated with a path, name filters, and entry filters. The path is the directory that the iterator lists entries in. The name filters and entry filters are provided for file engines that can optimize directory listing at the iterator level (e.g., network file systems that need to minimize network traffic), but they can also be ignored by the iterator subclass; QAbstractFileEngineIterator
already provides the required filtering logics in the matchesFilters()
function. You can call dirName()
to get the directory name, nameFilters()
to get a stringlist of name filters, and filters()
to get the entry filters. The pure virual function hasNext()
returns true if the current directory has at least one more entry (i.e., the directory name is valid and accessible, and we have not reached the end of the entry list), and false otherwise. Reimplement next()
to seek to the next entry.
The pure virtual function currentFileName()
returns the name of the current entry without advancing the iterator. The currentFilePath()
function is provided for convenience; it returns the full path of the current entry.
Here is an example of how to implement an interator that returns each of three fixed entries in sequence.
class CustomIterator extends QAbstractFileEngineIterator { private java.util.List<String> entries; private int index; public CustomIterator(java.util.List<String> nameFilters, QDir.Filters filters) { super(filters, nameFilters); index = 0; // In a real iterator, these entries are fetched from the // file system based on the value of path(). entries.add("entry1"); entries.add("entry2"); entries.add("entry3"); } public boolean hasNext() { return index < entries.size() - 1; } public String next() { if (!hasNext()) return ""; ++index; return currentFilePath(); } public String currentFileName() { return entries.get(index); } }Note:
QAbstractFileEngineIterator
does not deal with QDir::IteratorFlags
; it simply returns entries for a single directory. QDirIterator
.
Nested Class Summary |
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Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
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QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9 |
Constructor Summary | |
---|---|
QAbstractFileEngineIterator(QDir.Filters filters,
java.util.List nameFilters)
Constructs a QAbstractFileEngineIterator , using the entry filters filters, and wildcard name filters nameFilters. |
Method Summary | |
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QFileInfo |
currentFileInfo()
The virtual function returns a QFileInfo for the current directory entry. |
abstract java.lang.String |
currentFileName()
This pure virtual function returns the name of the current directory entry, excluding the path. |
java.lang.String |
currentFilePath()
Returns the path to the current directory entry. |
QDir.Filters |
filters()
Returns the entry filters for this iterator. |
static QAbstractFileEngineIterator |
fromNativePointer(QNativePointer nativePointer)
|
abstract boolean |
hasNext()
This pure virtual function returns true if there is at least one more entry in the current directory (i.e., the iterator path is valid and accessible, and the iterator has not reached the end of the entry list). |
java.util.List |
nameFilters()
Returns the name filters for this iterator. |
abstract java.lang.String |
next()
This pure virtual function advances the iterator to the next directory entry, and returns the file path to the current entry. |
java.lang.String |
path()
Returns the path for this iterator. |
Methods inherited from class com.trolltech.qt.QtJambiObject |
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dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
---|
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread |
Methods inherited from class java.lang.Object |
---|
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
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disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
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public QAbstractFileEngineIterator(QDir.Filters filters, java.util.List nameFilters)
QAbstractFileEngineIterator
, using the entry filters filters, and wildcard name filters nameFilters.
Method Detail |
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public final java.lang.String currentFilePath()
path()
to the return value of currentFileName()
. currentFileName()
.
public final QDir.Filters filters()
QDir::filter()
, nameFilters()
, and path()
.
public final java.util.List nameFilters()
QDir::nameFilters()
, filters()
, and path()
.
public final java.lang.String path()
QDirIterator
is responsible for assigning this path; it cannot change during the iterator's lifetime. nameFilters()
, and filters()
.
public QFileInfo currentFileInfo()
QFileInfo
for the current directory entry. This function is provided for convenience. It can also be slightly faster that creating a QFileInfo
object yourself, as the object returned by this function might contain cached information that QFileInfo
otherwise would have to access through the file engine. currentFileName()
.
public abstract java.lang.String currentFileName()
currentFilePath()
.
public abstract boolean hasNext()
QDirIterator::hasNext()
.
public abstract java.lang.String next()
This function can optionally make use of nameFilters()
and filters()
to optimize its performance.
Reimplement this function in a subclass to advance the iterator.
QDirIterator::next()
.
public static QAbstractFileEngineIterator fromNativePointer(QNativePointer nativePointer)
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