org.openide.filesystems

Class FileLock

java.lang.Object

org.openide.filesystems.FileLock

All Implemented Interfaces:

AutoCloseable

public class FileLock
extends Object
implements AutoCloseable

Represents an acquired lock on a FileObject. Typical usage includes locking the file in the editor on first modification, and then using this object to ensure exclusive access when overwriting the file (saving) by using FileObject.getOutputStream(org.openide.filesystems.FileLock). Also used for renames, deletes, &c.

Note that such locks are only used to protect against concurrent write accesses, and are not used for read operations (i.e. they are not write-one-read-many locks). Normally this is sufficient protection. If you really need an atomic read, you may simply lock the file, perform the read, and unlock it when done. The file will still be protected against writes, although the read operation did not request a lock.

The FileLock implements AutoCloseable, so it can be created within try-with-resources resource clause and the lock will be released at the end of the try block.

Since:

9.2 implements AutoCloseable interface.

See Also:

FileObject

Field Summary

Fields

Modifier and Type	Field and Description
protected Throwable	lockedBy
static FileLock	NONE Constant that can be used in filesystems that do not support locking.

Constructor Summary

Constructors

Constructor and Description
FileLock()

Method Summary

Modifier and Type	Method and Description
void	close() Releases the lock.
void	finalize() Finalize this object.
boolean	isValid() Test whether this lock is still active, or released.
void	releaseLock() Release this lock.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NONE

public static final FileLock NONE

Constant that can be used in filesystems that do not support locking. Represents a lock which is never valid.

lockedBy

protected Throwable lockedBy

Constructor Detail

FileLock

public FileLock()

Method Detail

releaseLock

public void releaseLock()

Release this lock. In typical usage this method will be called in a finally clause.

close

public void close()

Releases the lock. Equivalent to FileLock.releaseLock() call.

Specified by:

close in interface AutoCloseable

isValid

public boolean isValid()

Test whether this lock is still active, or released.

Returns:

true if lock is still active

finalize

public void finalize()

Finalize this object. Calls FileLock.releaseLock() to release the lock if the program for some reason failed to.

Overrides:

finalize in class Object