Module java.desktop
Package java.awt.dnd

Class 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.

    • Constructor Detail

      • 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​(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 Detail

      • 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

      • 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