Module java.desktop

Package java.awt.dnd

Class DropTarget

java.lang.Object

java.awt.dnd.DropTarget

All Implemented Interfaces:

DropTargetListener, Serializable, EventListener

public class DropTarget
extends Object
implements DropTargetListener, Serializable

The DropTarget is associated with a Component when that Component wishes to accept drops during Drag and Drop operations.

Each DropTarget is associated with a FlavorMap. The default FlavorMap hereafter designates the FlavorMap returned by SystemFlavorMap.getDefaultFlavorMap().

Since:

1.2

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	DropTarget.DropTargetAutoScroller	this protected nested class implements autoscrolling

Constructor Summary

Constructors

Constructor	Description
DropTarget()	Creates a DropTarget.
DropTarget(Component c, int ops, DropTargetListener dtl)	Creates a DropTarget given the Component to associate itself with, an int representing the default acceptable action(s) to support, and a DropTargetListener to handle event processing.
DropTarget(Component c, int ops, DropTargetListener dtl, boolean act)	Creates a DropTarget given the Component to associate itself with, an int representing the default acceptable action(s) to support, a DropTargetListener to handle event processing, and a boolean indicating if the DropTarget is currently accepting drops.
DropTarget(Component c, int ops, DropTargetListener dtl, boolean act, FlavorMap fm)	Creates a new DropTarget given the Component to associate itself with, an int representing the default acceptable action(s) to support, a DropTargetListener to handle event processing, a boolean indicating if the DropTarget is currently accepting drops, and a FlavorMap to use (or null for the default FlavorMap).
DropTarget(Component c, DropTargetListener dtl)	Creates a DropTarget given the Component to associate itself with, and the DropTargetListener to handle event processing.

Method Summary

Modifier and Type	Method	Description
void	addDropTargetListener(DropTargetListener dtl)	Adds a new DropTargetListener (UNICAST SOURCE).
void	addNotify()	Notify the DropTarget that it has been associated with a Component This method is usually called from java.awt.Component.addNotify() of the Component associated with this DropTarget to notify the DropTarget that a ComponentPeer has been associated with that Component.
protected void	clearAutoscroll()	clear autoscrolling
protected DropTarget.DropTargetAutoScroller	createDropTargetAutoScroller(Component c, Point p)	create an embedded autoscroller
protected DropTargetContext	createDropTargetContext()	Creates the DropTargetContext associated with this DropTarget.
void	dragEnter(DropTargetDragEvent dtde)	Calls dragEnter on the registered DropTargetListener and passes it the specified DropTargetDragEvent.
void	dragExit(DropTargetEvent dte)	Calls dragExit on the registered DropTargetListener and passes it the specified DropTargetEvent.
void	dragOver(DropTargetDragEvent dtde)	Calls dragOver on the registered DropTargetListener and passes it the specified DropTargetDragEvent.
void	drop(DropTargetDropEvent dtde)	Calls drop on the registered DropTargetListener and passes it the specified DropTargetDropEvent if this DropTarget is active.
void	dropActionChanged(DropTargetDragEvent dtde)	Calls dropActionChanged on the registered DropTargetListener and passes it the specified DropTargetDragEvent.
Component	getComponent()	Gets the Component associated with this DropTarget.
int	getDefaultActions()	Gets an int representing the current action(s) supported by this DropTarget.
DropTargetContext	getDropTargetContext()	Gets the DropTargetContext associated with this DropTarget.
FlavorMap	getFlavorMap()	Gets the FlavorMap associated with this DropTarget.
protected void	initializeAutoscrolling(Point p)	initialize autoscrolling
boolean	isActive()	Reports whether or not this DropTarget is currently active (ready to accept drops).
void	removeDropTargetListener(DropTargetListener dtl)	Removes the current DropTargetListener (UNICAST SOURCE).
void	removeNotify()	Notify the DropTarget that it has been disassociated from a Component This method is usually called from java.awt.Component.removeNotify() of the Component associated with this DropTarget to notify the DropTarget that a ComponentPeer has been disassociated with that Component.
void	setActive(boolean isActive)	Sets the DropTarget active if true, inactive if false.
void	setComponent(Component c)	Note: this interface is required to permit the safe association of a DropTarget with a Component in one of two ways, either: component.setDropTarget(droptarget); or droptarget.setComponent(component);
void	setDefaultActions(int ops)	Sets the default acceptable actions for this DropTarget
void	setFlavorMap(FlavorMap fm)	Sets the FlavorMap associated with this DropTarget.
protected void	updateAutoscroll(Point dragCursorLocn)	update autoscrolling with current cursor location

Methods declared in class java.lang.Object

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

Constructor Details

DropTarget

public DropTarget(Component c,
 int ops,
 DropTargetListener dtl,
 boolean act,
 FlavorMap fm)
           throws HeadlessException

Creates a new DropTarget given the Component to associate itself with, an int representing the default acceptable action(s) to support, a DropTargetListener to handle event processing, a boolean indicating if the DropTarget is currently accepting drops, and a FlavorMap to use (or null for the default FlavorMap).

The Component will receive drops only if it is enabled.

Parameters:

c - The Component with which this DropTarget is associated

ops - The default acceptable actions for this DropTarget

dtl - The DropTargetListener for this DropTarget

act - Is the DropTarget accepting drops.

fm - The FlavorMap to use, or null for the default FlavorMap

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

• GraphicsEnvironment.isHeadless()

DropTarget

public DropTarget(Component c,
 int ops,
 DropTargetListener dtl,
 boolean act)
           throws HeadlessException

Creates a DropTarget given the Component to associate itself with, an int representing the default acceptable action(s) to support, a DropTargetListener to handle event processing, and a boolean indicating if the DropTarget is currently accepting drops.

The Component will receive drops only if it is enabled.

Parameters:

c - The Component with which this DropTarget is associated

ops - The default acceptable actions for this DropTarget

dtl - The DropTargetListener for this DropTarget

act - Is the DropTarget accepting drops.

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

• GraphicsEnvironment.isHeadless()

DropTarget

public DropTarget()
           throws HeadlessException

Creates a DropTarget.

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

• GraphicsEnvironment.isHeadless()

DropTarget

public DropTarget(Component c,
 DropTargetListener dtl)
           throws HeadlessException

Creates a DropTarget given the Component to associate itself with, and the DropTargetListener to handle event processing.

The Component will receive drops only if it is enabled.

Parameters:

c - The Component with which this DropTarget is associated

dtl - The DropTargetListener for this DropTarget

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

• GraphicsEnvironment.isHeadless()

DropTarget

public DropTarget(Component c,
 int ops,
 DropTargetListener dtl)
           throws HeadlessException

Creates a DropTarget given the Component to associate itself with, an int representing the default acceptable action(s) to support, and a DropTargetListener to handle event processing.

The Component will receive drops only if it is enabled.

Parameters:

c - The Component with which this DropTarget is associated

ops - The default acceptable actions for this DropTarget

dtl - The DropTargetListener for this DropTarget

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true

See Also:

• GraphicsEnvironment.isHeadless()

Method Details

setComponent

public void setComponent(Component c)

Note: this interface is required to permit the safe association of a DropTarget with a Component in one of two ways, either: component.setDropTarget(droptarget); or droptarget.setComponent(component);

The Component will receive drops only if it is enabled.

Parameters:

c - The new Component this DropTarget is to be associated with.

getComponent

public Component getComponent()

Gets the Component associated with this DropTarget.

Returns:

the current Component

setDefaultActions

public void setDefaultActions(int ops)

Sets the default acceptable actions for this DropTarget

Parameters:

ops - the default actions

See Also:

• DnDConstants

getDefaultActions

public int getDefaultActions()

Gets an int representing the current action(s) supported by this DropTarget.

Returns:

the current default actions

setActive

public void setActive(boolean isActive)

Sets the DropTarget active if true, inactive if false.

Parameters:

isActive - sets the DropTarget (in)active.

isActive

public boolean isActive()

Reports whether or not this DropTarget is currently active (ready to accept drops).

Returns:

true if active, false if not

addDropTargetListener

public void addDropTargetListener(DropTargetListener dtl)
                           throws TooManyListenersException

Adds a new DropTargetListener (UNICAST SOURCE).

Parameters:

dtl - The new DropTargetListener

Throws:

TooManyListenersException - if a DropTargetListener is already added to this DropTarget.

removeDropTargetListener

public void removeDropTargetListener(DropTargetListener dtl)

Removes the current DropTargetListener (UNICAST SOURCE).

Parameters:

dtl - the DropTargetListener to deregister.

dragEnter

public void dragEnter(DropTargetDragEvent dtde)

Calls dragEnter on the registered DropTargetListener and passes it the specified DropTargetDragEvent. Has no effect if this DropTarget is not active.

Specified by:

dragEnter in interface DropTargetListener

Parameters:

dtde - the DropTargetDragEvent

Throws:

NullPointerException - if this DropTarget is active and dtde is null

See Also:

• isActive()

dragOver

public void dragOver(DropTargetDragEvent dtde)

Calls dragOver on the registered DropTargetListener and passes it the specified DropTargetDragEvent. Has no effect if this DropTarget is not active.

Specified by:

dragOver in interface DropTargetListener

Parameters:

dtde - the DropTargetDragEvent

Throws:

NullPointerException - if this DropTarget is active and dtde is null

See Also:

• isActive()

dropActionChanged

public void dropActionChanged(DropTargetDragEvent dtde)

Calls dropActionChanged on the registered DropTargetListener and passes it the specified DropTargetDragEvent. Has no effect if this DropTarget is not active.

Specified by:

dropActionChanged in interface DropTargetListener

Parameters:

dtde - the DropTargetDragEvent

Throws:

NullPointerException - if this DropTarget is active and dtde is null

See Also:

• isActive()

dragExit

public void dragExit(DropTargetEvent dte)

Calls dragExit on the registered DropTargetListener and passes it the specified DropTargetEvent. Has no effect if this DropTarget is not active.

This method itself does not throw any exception for null parameter but for exceptions thrown by the respective method of the listener.

Specified by:

dragExit in interface DropTargetListener

Parameters:

dte - the DropTargetEvent

See Also:

• isActive()

drop

public void drop(DropTargetDropEvent dtde)

Calls drop on the registered DropTargetListener and passes it the specified DropTargetDropEvent if this DropTarget is active.

Specified by:

drop in interface DropTargetListener

Parameters:

dtde - the DropTargetDropEvent

Throws:

NullPointerException - if dtde is null and at least one of the following is true: this DropTarget is not active, or there is no a DropTargetListener registered.

See Also:

• isActive()

getFlavorMap

public FlavorMap getFlavorMap()

Gets the FlavorMap associated with this DropTarget. If no FlavorMap has been set for this DropTarget, it is associated with the default FlavorMap.

Returns:

the FlavorMap for this DropTarget

setFlavorMap

public void setFlavorMap(FlavorMap fm)

Sets the FlavorMap associated with this DropTarget.

Parameters:

fm - the new FlavorMap, or null to associate the default FlavorMap with this DropTarget.

addNotify

public void addNotify()

Notify the DropTarget that it has been associated with a Component This method is usually called from java.awt.Component.addNotify() of the Component associated with this DropTarget to notify the DropTarget that a ComponentPeer has been associated with that Component. Calling this method, other than to notify this DropTarget of the association of the ComponentPeer with the Component may result in a malfunction of the DnD system.

removeNotify

public void removeNotify()

Notify the DropTarget that it has been disassociated from a Component This method is usually called from java.awt.Component.removeNotify() of the Component associated with this DropTarget to notify the DropTarget that a ComponentPeer has been disassociated with that Component. Calling this method, other than to notify this DropTarget of the disassociation of the ComponentPeer from the Component may result in a malfunction of the DnD system.

getDropTargetContext

public DropTargetContext getDropTargetContext()

Gets the DropTargetContext associated with this DropTarget.

Returns:

the DropTargetContext associated with this DropTarget.

createDropTargetContext

protected DropTargetContext createDropTargetContext()

Creates the DropTargetContext associated with this DropTarget. Subclasses may override this method to instantiate their own DropTargetContext subclass. This call is typically *only* called by the platform's DropTargetContextPeer as a drag operation encounters this DropTarget. Accessing the Context while no Drag is current has undefined results.

Returns:

the DropTargetContext associated with this DropTarget

createDropTargetAutoScroller

protected DropTarget.DropTargetAutoScroller createDropTargetAutoScroller(Component c,
 Point p)

create an embedded autoscroller

Parameters:

c - the Component

p - the Point

Returns:

an embedded autoscroller

initializeAutoscrolling

protected void initializeAutoscrolling(Point p)

initialize autoscrolling

Parameters:

p - the Point

updateAutoscroll

protected void updateAutoscroll(Point dragCursorLocn)

update autoscrolling with current cursor location

Parameters:

dragCursorLocn - the Point

clearAutoscroll

protected void clearAutoscroll()

clear autoscrolling