Class TransferHandler.TransferSupport

java.lang.Object

javax.swing.TransferHandler.TransferSupport

Enclosing class:

TransferHandler

public static final class TransferHandler.TransferSupport
extends Object

This class encapsulates all relevant details of a clipboard or drag and drop transfer, and also allows for customizing aspects of the drag and drop experience.

The main purpose of this class is to provide the information needed by a developer to determine the suitability of a transfer or to import the data contained within. But it also doubles as a controller for customizing properties during drag and drop, such as whether or not to show the drop location, and which drop action to use.

Developers typically need not create instances of this class. Instead, they are something provided by the DnD implementation to certain methods in TransferHandler.

Since:

1.6

See Also:

• TransferHandler.canImport(TransferHandler.TransferSupport)
• TransferHandler.importData(TransferHandler.TransferSupport)

Constructor Summary

Constructors

Constructor	Description
TransferSupport(Component component, Transferable transferable)	Create a TransferSupport with isDrop() false for the given component and Transferable.

Method Summary

Modifier and Type	Method	Description
Component	getComponent()	Returns the target component of this transfer.
DataFlavor[]	getDataFlavors()	Returns the data flavors for this transfer.
int	getDropAction()	Returns the action chosen for the drop, when this TransferSupport represents a drop.
TransferHandler.DropLocation	getDropLocation()	Returns the current (non-null) drop location for the component, when this TransferSupport represents a drop.
int	getSourceDropActions()	Returns the drag source's supported drop actions, when this TransferSupport represents a drop.
Transferable	getTransferable()	Returns the Transferable associated with this transfer.
int	getUserDropAction()	Returns the user drop action for the drop, when this TransferSupport represents a drop.
boolean	isDataFlavorSupported(DataFlavor df)	Returns whether or not the given data flavor is supported.
boolean	isDrop()	Returns whether or not this TransferSupport represents a drop operation.
void	setDropAction(int dropAction)	Sets the drop action for the transfer - which must represent a drop - to the given action, instead of the default user drop action.
void	setShowDropLocation(boolean showDropLocation)	Sets whether or not the drop location should be visually indicated for the transfer - which must represent a drop.

Methods declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Constructor Details

TransferSupport

public TransferSupport(Component component,
 Transferable transferable)

Create a TransferSupport with isDrop() false for the given component and Transferable.

Parameters:

component - the target component

transferable - the transferable

Throws:

NullPointerException - if either parameter is null

Method Details

isDrop

public boolean isDrop()

Returns whether or not this TransferSupport represents a drop operation.

Returns:

true if this is a drop operation, false otherwise.

getComponent

public Component getComponent()

Returns the target component of this transfer.

Returns:

the target component

getDropLocation

public TransferHandler.DropLocation getDropLocation()

Returns the current (non-null) drop location for the component, when this TransferSupport represents a drop.

Note: For components with built-in drop support, this location will be a subclass of DropLocation of the same type returned by that component's getDropLocation method.

This method is only for use with drag and drop transfers. Calling it when isDrop() is false results in an IllegalStateException.

Returns:

the drop location

Throws:

IllegalStateException - if this is not a drop

See Also:

• isDrop()

setShowDropLocation

public void setShowDropLocation(boolean showDropLocation)

Sets whether or not the drop location should be visually indicated for the transfer - which must represent a drop. This is applicable to those components that automatically show the drop location when appropriate during a drag and drop operation. By default, the drop location is shown only when the TransferHandler has said it can accept the import represented by this TransferSupport. With this method you can force the drop location to always be shown, or always not be shown.

This method is only for use with drag and drop transfers. Calling it when isDrop() is false results in an IllegalStateException.

Parameters:

showDropLocation - whether or not to indicate the drop location

Throws:

IllegalStateException - if this is not a drop

See Also:

• isDrop()

setDropAction

public void setDropAction(int dropAction)

Sets the drop action for the transfer - which must represent a drop - to the given action, instead of the default user drop action. The action must be supported by the source's drop actions, and must be one of COPY, MOVE or LINK.

This method is only for use with drag and drop transfers. Calling it when isDrop() is false results in an IllegalStateException.

Parameters:

dropAction - the drop action

Throws:

IllegalStateException - if this is not a drop

IllegalArgumentException - if an invalid action is specified

See Also:

• getDropAction()
• getUserDropAction()
• getSourceDropActions()
• isDrop()

getDropAction

public int getDropAction()

Returns the action chosen for the drop, when this TransferSupport represents a drop.

Unless explicitly chosen by way of setDropAction, this returns the user drop action provided by getUserDropAction.

You may wish to query this in TransferHandler's importData method to customize processing based on the action.

This method is only for use with drag and drop transfers. Calling it when isDrop() is false results in an IllegalStateException.

Returns:

the action chosen for the drop

Throws:

IllegalStateException - if this is not a drop

See Also:

• setDropAction(int)
• getUserDropAction()
• isDrop()

getUserDropAction

public int getUserDropAction()

Returns the user drop action for the drop, when this TransferSupport represents a drop.

The user drop action is chosen for a drop as described in the documentation for DropTargetDragEvent and DropTargetDropEvent. A different action may be chosen as the drop action by way of the setDropAction method.

You may wish to query this in TransferHandler's canImport method when determining the suitability of a drop or when deciding on a drop action to explicitly choose.

This method is only for use with drag and drop transfers. Calling it when isDrop() is false results in an IllegalStateException.

Returns:

the user drop action

Throws:

IllegalStateException - if this is not a drop

See Also:

• setDropAction(int)
• getDropAction()
• isDrop()

getSourceDropActions

public int getSourceDropActions()

Returns the drag source's supported drop actions, when this TransferSupport represents a drop.

The source actions represent the set of actions supported by the source of this transfer, and are represented as some bitwise-OR combination of COPY, MOVE and LINK. You may wish to query this in TransferHandler's canImport method when determining the suitability of a drop or when deciding on a drop action to explicitly choose. To determine if a particular action is supported by the source, bitwise-AND the action with the source drop actions, and then compare the result against the original action. For example:

boolean copySupported = (COPY & getSourceDropActions()) == COPY;

This method is only for use with drag and drop transfers. Calling it when isDrop() is false results in an IllegalStateException.

Returns:

the drag source's supported drop actions

Throws:

IllegalStateException - if this is not a drop

See Also:

• isDrop()

getDataFlavors

public DataFlavor[] getDataFlavors()

Returns the data flavors for this transfer.

Returns:

the data flavors for this transfer

isDataFlavorSupported

public boolean isDataFlavorSupported(DataFlavor df)

Returns whether or not the given data flavor is supported.

Parameters:

df - the DataFlavor to test

Returns:

whether or not the given flavor is supported.

getTransferable

public Transferable getTransferable()

Returns the Transferable associated with this transfer.

Note: Unless it is necessary to fetch the Transferable directly, use one of the other methods on this class to inquire about the transfer. This may perform better than fetching the Transferable and asking it directly.

Returns:

the Transferable associated with this transfer