Class 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

All Methods Instance Methods Concrete Methods
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 java.lang.Object

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

Constructor Detail

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 Detail

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