DropTarget (Java Platform SE 8 )
Keywords: java.awt.dnd.DropTarget class
Date: 2017-01-22

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 and Description
    --- | ---
    `protected static class` | `DropTarget.DropTargetAutoScroller` this protected nested class implements autoscrolling

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `DropTarget()` Creates a `DropTarget`.
    `DropTarget(Component c, DropTargetListener dtl)` Creates a `DropTarget` given the `Component` to associate itself with, and the `DropTargetListener` to handle event processing.
    `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`).

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addDropTargetListener(DropTargetListener dtl)` Adds a new `DropTargetListener` (UNICAST SOURCE).
    `void` | `addNotify(java.awt.peer.ComponentPeer peer)` 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(java.awt.peer.ComponentPeer peer)` 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 inherited from class java.lang.Object

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

- - ### 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()
                     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 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

    - #### 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(java.awt.peer.ComponentPeer peer)

      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.

      Parameters:
        `peer` - The Peer of the Component we are associated with!

    - #### removeNotify

          public void removeNotify(java.awt.peer.ComponentPeer peer)

      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.

      Parameters:
        `peer` - The Peer of the Component we are being disassociated from!

    - #### 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.

    - #### createDropTargetAutoScroller

          protected DropTarget.DropTargetAutoScroller createDropTargetAutoScroller(Component c,
                                                                                   Point p)

      create an embedded autoscroller

      Parameters:
        `c` - the `Component`
        `p` - the `Point`

    - #### 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

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