com.trolltech.qt.core
Class QFileSystemWatcher

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.core.QFileSystemWatcher
All Implemented Interfaces:
QtJambiInterface

public class QFileSystemWatcher
extends QObject

The QFileSystemWatcher class provides an interface for monitoring files and directories for modifications. QFileSystemWatcher monitors the file system for changes to files and directories by watching a list of specified paths.

Call addPath() to watch a particular file or directory. Multiple paths can be added using the addPaths() function. Existing paths can be removed by using the removePath() and removePaths() functions.

QFileSystemWatcher examines each path added to it. Files that have been added to the QFileSystemWatcher can be accessed using the files() function, and directories using the directories() function.

The fileChanged() signal is emitted when a file has been modified, renamed or removed from disk. Similarly, the directoryChanged() signal is emitted when a directory or its contents is modified or removed. Note that QFileSystemWatcher stops monitoring files once they have been renamed or removed from disk, and directories once they have been removed from disk.

Note: On systems running a Linux kernel without inotify support, file systems that contain watched paths cannot be unmounted.

Note: Windows CE does not support directory monitoring by default as this depends on the file system driver installed.

Note: The act of monitoring files and directories for modifications consumes system resources. This implies there is a limit to the number of files and directories your process can monitor simultaneously. On Mac OS and all BSD variants, for example, an open file descriptor is required for each monitored file. The system limits the number of open file descriptors to 256 by default. This means that addPath() and addPaths() will fail if your process tries to add more than 256 files or directories to the file system monitor. Also note that your process may have other file descriptors open in addition to the ones for files being monitored, and these other open descriptors also count in the total.

See also:
QFile, and QDir.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 QSignalEmitter.Signal1 directoryChanged
          This signal takes 1 generic argument(s).
 QSignalEmitter.Signal1 fileChanged
          This signal takes 1 generic argument(s).
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QFileSystemWatcher()
          Constructs a new file system watcher object with the given parent.
QFileSystemWatcher(java.util.List paths)
          Constructs a new file system watcher object with the given parent which monitors the specified paths list.
QFileSystemWatcher(java.util.List paths, QObject parent)
          Constructs a new file system watcher object with the given parent which monitors the specified paths list.
QFileSystemWatcher(QObject parent)
          Constructs a new file system watcher object with the given parent.
 
Method Summary
 void addPath(java.lang.String file)
          Adds path to the file system watcher if path exists.
 void addPaths(java.util.List files)
          Adds each path in paths to the file system watcher.
 java.util.List directories()
          Returns a list of paths to directories that are being watched.
 java.util.List files()
          Returns a list of paths to files that are being watched.
 void removePath(java.lang.String file)
          Removes the specified path from the file system watcher.
 void removePaths(java.util.List files)
          Removes the specified paths from the file system watcher.
 
Methods inherited from class com.trolltech.qt.core.QObject
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty
 
Methods inherited from class com.trolltech.qt.QtJambiObject
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 com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Field Detail

directoryChanged

public final QSignalEmitter.Signal1 directoryChanged

This signal takes 1 generic argument(s). We list their type and the name they go by in the description of this signal. <java.lang.String(named: path)>:

This signal is emitted when the directory at a specified path, is modified (e. ., when a file is added, modified or deleted) or removed from disk. Note that if there are several changes during a short period of time, some of the changes might not emit this signal. However, the last change in the sequence of changes will always generate this signal.

See also:
fileChanged() .


fileChanged

public final QSignalEmitter.Signal1 fileChanged

This signal takes 1 generic argument(s). We list their type and the name they go by in the description of this signal. <java.lang.String(named: path)>:

This signal is emitted when the file at the specified path is modified, renamed or removed from disk.

See also:
directoryChanged() .

Constructor Detail

QFileSystemWatcher

public QFileSystemWatcher()
Constructs a new file system watcher object with the given parent.


QFileSystemWatcher

public QFileSystemWatcher(QObject parent)
Constructs a new file system watcher object with the given parent.


QFileSystemWatcher

public QFileSystemWatcher(java.util.List paths)
Constructs a new file system watcher object with the given parent which monitors the specified paths list.


QFileSystemWatcher

public QFileSystemWatcher(java.util.List paths,
                          QObject parent)
Constructs a new file system watcher object with the given parent which monitors the specified paths list.

Method Detail

addPath

public final void addPath(java.lang.String file)
Adds path to the file system watcher if path exists. The path is not added if it does not exist, or if it is already being monitored by the file system watcher.

If path specifies a directory, the directoryChanged() signal will be emitted when path is modified or removed from disk; otherwise the fileChanged() signal is emitted when path is modified, renamed or removed.

Note: There is a system dependent limit to the number of files and directories that can be monitored simultaneously. If this limit has been reached, path will not be added to the file system watcher, and a warning message will be printed to stderr.

See also:
addPaths(), and removePath().


addPaths

public final void addPaths(java.util.List files)
Adds each path in paths to the file system watcher. Paths are not added if they not exist, or if they are already being monitored by the file system watcher.

If a path specifies a directory, the directoryChanged() signal will be emitted when the path is modified or removed from disk; otherwise the fileChanged() signal is emitted when the path is modified, renamed, or removed.

Note: There is a system dependent limit to the number of files and directories that can be monitored simultaneously. If this limit has been reached, the excess paths will not be added to the file system watcher, and a warning message will be printed to stderr for each path that could not be added.

See also:
addPath(), and removePaths().


directories

public final java.util.List directories()
Returns a list of paths to directories that are being watched.

See also:
files().


files

public final java.util.List files()
Returns a list of paths to files that are being watched.

See also:
directories().


removePath

public final void removePath(java.lang.String file)
Removes the specified path from the file system watcher.

See also:
removePaths(), and addPath().


removePaths

public final void removePaths(java.util.List files)
Removes the specified paths from the file system watcher.

See also:
removePath(), and addPaths().