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