OpenJDK 27 · java.awt.dnd.DragGestureRecognizer · APIdia, the JavaDoc alternative

The DragGestureRecognizer is an abstract base class for the specification of a platform-dependent listener that can be associated with a particular Component in order to identify platform-dependent drag initiating gestures.

The appropriate DragGestureRecognizer subclass instance is obtained from the DragSource associated with a particular Component, or from the Toolkit object via its createDragGestureRecognizer() method.

Once the DragGestureRecognizer is associated with a particular Component it will register the appropriate listener interfaces on that Component in order to track the input events delivered to the Component.

Once the DragGestureRecognizer identifies a sequence of events on the Component as a drag initiating gesture, it will notify its unicast DragGestureListener by invoking its gestureRecognized() method.

When a concrete DragGestureRecognizer instance detects a drag initiating gesture on the Component it is associated with, it fires a DragGestureEvent to the DragGestureListener registered on its unicast event source for DragGestureListener events. This DragGestureListener is responsible for causing the associated DragSource to start the Drag and Drop operation (if appropriate).

Field Summary

Modifier and Type	Field and Description
protected Component	component The `Component` associated with this `DragGestureRecognizer`.
protected transient DragGestureListener	dragGestureListener The `DragGestureListener` associated with this `DragGestureRecognizer`.
protected DragSource	dragSource The `DragSource` associated with this `DragGestureRecognizer`.
protected ArrayList<InputEvent>	events The list of events (in order) that the `DragGestureRecognizer` "recognized" as a "gesture" that triggers a drag.
private static final long	serialVersionUID Use serialVersionUID from JDK 1.4 for interoperability.
protected int	sourceActions An `int` representing the type(s) of action(s) used in this Drag and Drop operation.

Constructor Summary

Access	Constructor and Description
protected	DragGestureRecognizer(DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation ds, Component the `Component` this `DragGestureRecognizer` should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is `null`, the `DragGestureRecognizer` is not associated with any `Component`. c, int the set (logical OR) of the `DnDConstants` that this Drag and Drop operation will support sa, DragGestureListener the `DragGestureRecognizer` to notify when a drag gesture is detected dgl) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation, the `Component` this `DragGestureRecognizer` should "observe" for drag initiating gestures, the action(s) supported for this Drag and Drop operation, and the `DragGestureListener` to notify once a drag initiating gesture has been detected.
protected	DragGestureRecognizer(DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation ds, Component the `Component` this `DragGestureRecognizer` should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is `null`, the `DragGestureRecognizer` is not associated with any `Component`. c, int the set (logical OR) of the `DnDConstants` that this Drag and Drop operation will support sa) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation, the `Component` this `DragGestureRecognizer` should "observe" for drag initiating gestures, and the action(s) supported for this Drag and Drop operation.
protected	DragGestureRecognizer(DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation ds, Component the `Component` this `DragGestureRecognizer` should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is `null`, the `DragGestureRecognizer` is not associated with any `Component`. c) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation, and the `Component` this `DragGestureRecognizer` should "observe" for drag initiating gestures.
protected	DragGestureRecognizer(DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation ds) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation.

Method Summary

Modifier and Type	Method and Description
public synchronized void	addDragGestureListener(DragGestureListener the `DragGestureListener` to register with this `DragGestureRecognizer`. dgl) Register a new `DragGestureListener`.
protected synchronized void	appendEvent(InputEvent the `InputEvent` to add to this `DragGestureRecognizer`'s internal array of events. Note that `null` is not a valid value, and will be ignored. awtie) Listeners registered on the Component by this Recognizer shall record all Events that are recognized as part of the series of Events that go to comprise a Drag and Drop initiating gesture via this API.
protected synchronized void	fireDragGestureRecognized(int The action initially selected by the users gesture dragAction, Point The point (in Component coords) where the gesture originated p) Notify the DragGestureListener that a Drag and Drop initiating gesture has occurred.
public synchronized Component	Returns: The Component this DragGestureRecognizer is associated with getComponent() This method returns the `Component` that is to be "observed" by the `DragGestureRecognizer` for drag initiating gestures.
public DragSource	Returns: the DragSource getDragSource() This method returns the `DragSource` this `DragGestureRecognizer` will use in order to process the Drag and Drop operation.
public synchronized int	Returns: the currently permitted source action(s) getSourceActions() This method returns an int representing the type of action(s) this Drag and Drop operation will support.
public InputEvent	Returns: the initial event that triggered the drag gesture getTriggerEvent() This method returns the first event in the series of events that initiated the Drag and Drop operation.
private void	readObject(ObjectInputStream the `ObjectInputStream` to read s) Deserializes this `DragGestureRecognizer`.
protected abstract void	registerListeners() register this DragGestureRecognizer's Listeners with the Component subclasses must override this method
public synchronized void	removeDragGestureListener(DragGestureListener the `DragGestureListener` to unregister from this `DragGestureRecognizer` dgl) unregister the current DragGestureListener
public void	resetRecognizer() Reset the Recognizer, if its currently recognizing a gesture, ignore it.
public synchronized void	setComponent(Component The `Component` or `null` c) set the Component that the DragGestureRecognizer is associated with registerListeners() and unregisterListeners() are called as a side effect as appropriate.
public synchronized void	setSourceActions(int the permitted source drag action(s) actions) This method sets the permitted source drag action(s) for this Drag and Drop operation.
protected abstract void	unregisterListeners() unregister this DragGestureRecognizer's Listeners with the Component subclasses must override this method
private void	writeObject(ObjectOutputStream the `ObjectOutputStream` to write s) Serializes this `DragGestureRecognizer`.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

component	back to summary
protected Component component The `Component` associated with this `DragGestureRecognizer`.

dragGestureListener	back to summary
protected transient DragGestureListener dragGestureListener The `DragGestureListener` associated with this `DragGestureRecognizer`.

dragSource	back to summary
protected DragSource dragSource The `DragSource` associated with this `DragGestureRecognizer`.

events	back to summary
protected ArrayList<InputEvent> events The list of events (in order) that the `DragGestureRecognizer` "recognized" as a "gesture" that triggers a drag.

serialVersionUID	back to summary
private static final long serialVersionUID Use serialVersionUID from JDK 1.4 for interoperability. Annotations @Serial

sourceActions	back to summary
protected int sourceActions An `int` representing the type(s) of action(s) used in this Drag and Drop operation.

Constructor Detail

DragGestureRecognizer back to summary

DragGestureRecognizer	back to summary
protected DragGestureRecognizer(DragSource ds, Component c, int sa, DragGestureListener dgl) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation, the `Component` this `DragGestureRecognizer` should "observe" for drag initiating gestures, the action(s) supported for this Drag and Drop operation, and the `DragGestureListener` to notify once a drag initiating gesture has been detected. Parameters ds:DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation c:Component the `Component` this `DragGestureRecognizer` should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is `null`, the `DragGestureRecognizer` is not associated with any `Component`. sa:int the set (logical OR) of the `DnDConstants` that this Drag and Drop operation will support dgl:DragGestureListener the `DragGestureRecognizer` to notify when a drag gesture is detected Exceptions IllegalArgumentException: if ds is `null`.

protected DragGestureRecognizer(DragSource ds, Component c, int sa, DragGestureListener dgl)

Construct a new DragGestureRecognizer given the DragSource to be used in this Drag and Drop operation, the Component this DragGestureRecognizer should "observe" for drag initiating gestures, the action(s) supported for this Drag and Drop operation, and the DragGestureListener to notify once a drag initiating gesture has been detected.

Parameters

ds:DragSource: the DragSource this DragGestureRecognizer will use to process the Drag and Drop operation
c:Component: the Component this DragGestureRecognizer should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is null, the DragGestureRecognizer is not associated with any Component.
sa:int: the set (logical OR) of the DnDConstants that this Drag and Drop operation will support
dgl:DragGestureListener: the DragGestureRecognizer to notify when a drag gesture is detected

Exceptions

IllegalArgumentException:: if ds is null.

DragGestureRecognizer back to summary

DragGestureRecognizer	back to summary
protected DragGestureRecognizer(DragSource ds, Component c, int sa) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation, the `Component` this `DragGestureRecognizer` should "observe" for drag initiating gestures, and the action(s) supported for this Drag and Drop operation. Parameters ds:DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation c:Component the `Component` this `DragGestureRecognizer` should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is `null`, the `DragGestureRecognizer` is not associated with any `Component`. sa:int the set (logical OR) of the `DnDConstants` that this Drag and Drop operation will support Exceptions IllegalArgumentException: if ds is `null`.

protected DragGestureRecognizer(DragSource ds, Component c, int sa)

Construct a new DragGestureRecognizer given the DragSource to be used in this Drag and Drop operation, the Component this DragGestureRecognizer should "observe" for drag initiating gestures, and the action(s) supported for this Drag and Drop operation.

Parameters

ds:DragSource: the DragSource this DragGestureRecognizer will use to process the Drag and Drop operation
c:Component: the Component this DragGestureRecognizer should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is null, the DragGestureRecognizer is not associated with any Component.
sa:int: the set (logical OR) of the DnDConstants that this Drag and Drop operation will support

Exceptions

IllegalArgumentException:: if ds is null.

DragGestureRecognizer back to summary

DragGestureRecognizer	back to summary
protected DragGestureRecognizer(DragSource ds, Component c) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation, and the `Component` this `DragGestureRecognizer` should "observe" for drag initiating gestures. Parameters ds:DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation c:Component the `Component` this `DragGestureRecognizer` should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is `null`, the `DragGestureRecognizer` is not associated with any `Component`. Exceptions IllegalArgumentException: if ds is `null`.

protected DragGestureRecognizer(DragSource ds, Component c)

Construct a new DragGestureRecognizer given the DragSource to be used in this Drag and Drop operation, and the Component this DragGestureRecognizer should "observe" for drag initiating gestures.

Parameters

ds:DragSource: the DragSource this DragGestureRecognizer will use to process the Drag and Drop operation
c:Component: the Component this DragGestureRecognizer should "observe" the event stream to, in order to detect a drag initiating gesture. If this value is null, the DragGestureRecognizer is not associated with any Component.

Exceptions

IllegalArgumentException:: if ds is null.

DragGestureRecognizer back to summary

DragGestureRecognizer	back to summary
protected DragGestureRecognizer(DragSource ds) Construct a new `DragGestureRecognizer` given the `DragSource` to be used in this Drag and Drop operation. Parameters ds:DragSource the `DragSource` this `DragGestureRecognizer` will use to process the Drag and Drop operation Exceptions IllegalArgumentException: if ds is `null`.

protected DragGestureRecognizer(DragSource ds)

Construct a new DragGestureRecognizer given the DragSource to be used in this Drag and Drop operation.

Parameters

ds:DragSource: the DragSource this DragGestureRecognizer will use to process the Drag and Drop operation

Exceptions

IllegalArgumentException:: if ds is null.

Method Detail

addDragGestureListener back to summary

addDragGestureListener	back to summary
public synchronized void addDragGestureListener(DragGestureListener dgl) throws TooManyListenersException Register a new `DragGestureListener`. Parameters dgl:DragGestureListener the `DragGestureListener` to register with this `DragGestureRecognizer`. Exceptions TooManyListenersException: if a `DragGestureListener` has already been added.

public synchronized void addDragGestureListener(DragGestureListener dgl) throws TooManyListenersException

Parameters

dgl:DragGestureListener: the DragGestureListener to register with this DragGestureRecognizer.

Exceptions

TooManyListenersException:: if a DragGestureListener has already been added.

appendEvent back to summary

appendEvent	back to summary
protected synchronized void appendEvent(InputEvent awtie) Listeners registered on the Component by this Recognizer shall record all Events that are recognized as part of the series of Events that go to comprise a Drag and Drop initiating gesture via this API. This method is used by a `DragGestureRecognizer` implementation to add an `InputEvent` subclass (that it believes is one in a series of events that comprise a Drag and Drop operation) to the array of events that this `DragGestureRecognizer` maintains internally. Parameters awtie:InputEvent the `InputEvent` to add to this `DragGestureRecognizer`'s internal array of events. Note that `null` is not a valid value, and will be ignored.

protected synchronized void appendEvent(InputEvent awtie)

Listeners registered on the Component by this Recognizer shall record all Events that are recognized as part of the series of Events that go to comprise a Drag and Drop initiating gesture via this API.

This method is used by a DragGestureRecognizer implementation to add an InputEvent subclass (that it believes is one in a series of events that comprise a Drag and Drop operation) to the array of events that this DragGestureRecognizer maintains internally.

Parameters

awtie:InputEvent: the InputEvent to add to this DragGestureRecognizer's internal array of events. Note that null is not a valid value, and will be ignored.

fireDragGestureRecognized	back to summary
protected synchronized void fireDragGestureRecognized(int dragAction, Point p) Notify the DragGestureListener that a Drag and Drop initiating gesture has occurred. Then reset the state of the Recognizer. Parameters dragAction:int The action initially selected by the users gesture p:Point The point (in Component coords) where the gesture originated

fireDragGestureRecognized

back to summary

protected synchronized void fireDragGestureRecognized(int dragAction, Point p)

Notify the DragGestureListener that a Drag and Drop initiating gesture has occurred. Then reset the state of the Recognizer.

Parameters

dragAction:int: The action initially selected by the users gesture
p:Point: The point (in Component coords) where the gesture originated

getComponent back to summary

getComponent	back to summary
public synchronized Component getComponent() This method returns the `Component` that is to be "observed" by the `DragGestureRecognizer` for drag initiating gestures. Returns:Component The Component this DragGestureRecognizer is associated with

public synchronized Component getComponent()

This method returns the Component that is to be "observed" by the DragGestureRecognizer for drag initiating gestures.

Returns:Component: The Component this DragGestureRecognizer is associated with

getDragSource back to summary

getDragSource	back to summary
public DragSource getDragSource() This method returns the `DragSource` this `DragGestureRecognizer` will use in order to process the Drag and Drop operation. Returns:DragSource the DragSource

public DragSource getDragSource()

This method returns the DragSource this DragGestureRecognizer will use in order to process the Drag and Drop operation.

Returns:DragSource: the DragSource

getSourceActions	back to summary
public synchronized int getSourceActions() This method returns an int representing the type of action(s) this Drag and Drop operation will support. Returns:int the currently permitted source action(s)

getSourceActions

back to summary

public synchronized int getSourceActions()

This method returns an int representing the type of action(s) this Drag and Drop operation will support.

Returns:int: the currently permitted source action(s)

getTriggerEvent	back to summary
public InputEvent getTriggerEvent() This method returns the first event in the series of events that initiated the Drag and Drop operation. Returns:InputEvent the initial event that triggered the drag gesture

getTriggerEvent

back to summary

public InputEvent getTriggerEvent()

This method returns the first event in the series of events that initiated the Drag and Drop operation.

Returns:InputEvent: the initial event that triggered the drag gesture

readObject back to summary

readObject	back to summary
private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException Deserializes this `DragGestureRecognizer`. This method first performs default deserialization for all non-`transient` fields. This object's `DragGestureListener` is then deserialized as well by using the next object in the stream. Parameters s:ObjectInputStream the `ObjectInputStream` to read Annotations @Serial @SuppressWarnings:unchecked Exceptions ClassNotFoundException: if the class of a serialized object could not be found IOException: if an I/O error occurs Since 1.4

private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException

Deserializes this DragGestureRecognizer. This method first performs default deserialization for all non-transient fields. This object's DragGestureListener is then deserialized as well by using the next object in the stream.

Parameters

s:ObjectInputStream: the ObjectInputStream to read

Annotations

@Serial
@SuppressWarnings:unchecked

Exceptions

ClassNotFoundException:: if the class of a serialized object could not be found
IOException:: if an I/O error occurs

Since

1.4

registerListeners	back to summary
protected abstract void registerListeners() register this DragGestureRecognizer's Listeners with the Component subclasses must override this method

removeDragGestureListener back to summary

removeDragGestureListener	back to summary
public synchronized void removeDragGestureListener(DragGestureListener dgl) unregister the current DragGestureListener Parameters dgl:DragGestureListener the `DragGestureListener` to unregister from this `DragGestureRecognizer` Exceptions IllegalArgumentException: if dgl is not (equal to) the currently registered `DragGestureListener`.

public synchronized void removeDragGestureListener(DragGestureListener dgl)

unregister the current DragGestureListener

Parameters

dgl:DragGestureListener: the DragGestureListener to unregister from this DragGestureRecognizer

Exceptions

IllegalArgumentException:: if dgl is not (equal to) the currently registered DragGestureListener.

resetRecognizer	back to summary
public void resetRecognizer() Reset the Recognizer, if its currently recognizing a gesture, ignore it.

setComponent back to summary

setComponent	back to summary
public synchronized void setComponent(Component c) set the Component that the DragGestureRecognizer is associated with registerListeners() and unregisterListeners() are called as a side effect as appropriate. Parameters c:Component The `Component` or `null`

public synchronized void setComponent(Component c)

set the Component that the DragGestureRecognizer is associated with registerListeners() and unregisterListeners() are called as a side effect as appropriate.

Parameters

c:Component: The Component or null

setSourceActions	back to summary
public synchronized void setSourceActions(int actions) This method sets the permitted source drag action(s) for this Drag and Drop operation. Parameters actions:int the permitted source drag action(s)

setSourceActions

back to summary

public synchronized void setSourceActions(int actions)

This method sets the permitted source drag action(s) for this Drag and Drop operation.

Parameters

actions:int: the permitted source drag action(s)

unregisterListeners	back to summary
protected abstract void unregisterListeners() unregister this DragGestureRecognizer's Listeners with the Component subclasses must override this method

writeObject back to summary

writeObject	back to summary
private void writeObject(ObjectOutputStream s) throws IOException Serializes this `DragGestureRecognizer`. This method first performs default serialization. Then, this object's `DragGestureListener` is written out if and only if it can be serialized. If not, `null` is written instead. Parameters s:ObjectOutputStream the `ObjectOutputStream` to write Annotations @Serial Exceptions IOException: if an I/O error occurs Since 1.4 Serial data The default serializable fields, in alphabetical order, followed by either a `DragGestureListener`, or `null`.

private void writeObject(ObjectOutputStream s) throws IOException

Serializes this DragGestureRecognizer. This method first performs default serialization. Then, this object's DragGestureListener is written out if and only if it can be serialized. If not, null is written instead.

Parameters

s:ObjectOutputStream: the ObjectOutputStream to write

Annotations

@Serial

Exceptions

IOException:: if an I/O error occurs

Since

1.4

Serial data

The default serializable fields, in alphabetical order, followed by either a DragGestureListener, or null.

public abstract Class DragGestureRecognizer

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail