TransferHandler
public static final class TransferHandler.TransferSupport extends Object
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
.
Constructor | Description |
---|---|
TransferSupport |
Create a TransferSupport with isDrop() false for the given component and Transferable . |
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 |
Returns whether or not the given data flavor is supported. |
boolean |
isDrop() |
Returns whether or not this TransferSupport represents a drop operation. |
void |
setDropAction |
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 |
Sets whether or not the drop location should be visually indicated for the transfer - which must represent a drop. |
public TransferSupport(Component component, Transferable transferable)
TransferSupport
with isDrop()
false
for the given component and Transferable
.component
- the target componenttransferable
- the transferableNullPointerException
- if either parameter is null
public boolean isDrop()
TransferSupport
represents a drop operation.true
if this is a drop operation, false
otherwise.public Component getComponent()
public TransferHandler.DropLocation getDropLocation()
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
.
IllegalStateException
- if this is not a droppublic void setShowDropLocation(boolean showDropLocation)
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
.
showDropLocation
- whether or not to indicate the drop locationIllegalStateException
- if this is not a droppublic void setDropAction(int dropAction)
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
.
dropAction
- the drop actionIllegalStateException
- if this is not a dropIllegalArgumentException
- if an invalid action is specifiedpublic int getDropAction()
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
.
IllegalStateException
- if this is not a droppublic int getUserDropAction()
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
.
IllegalStateException
- if this is not a droppublic int getSourceDropActions()
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
.
IllegalStateException
- if this is not a droppublic DataFlavor[] getDataFlavors()
public boolean isDataFlavorSupported(DataFlavor df)
df
- the DataFlavor
to testpublic Transferable getTransferable()
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.
Transferable
associated with this transfer
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/swing/TransferHandler.TransferSupport.html