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16.4 Clipboard

The Clipboard class is a repository for a Transferable object and can be used for cut, copy, and paste operations. You can work with a private clipboard by creating your own instance of Clipboard, or you can work with the system clipboard by asking the Toolkit for it:

Toolkit.getDefaultToolkit().getSystemClipboard()

When working with the system clipboard, native applications have access to information created within Java programs and vice versa. Access to the system clipboard is controlled by the SecurityManager and is restricted within applets.

Clipboard Methods

Variables

protected ClipboardOwner owner (New)

The owner instance variable represents the current owner of contents. When something new is placed on the clipboard, the previous owner is notified by a call to the lostOwnership() method. The owner usually ignores this notification. However, the clipboard's contents are passed back to owner in case some special processing or comparison needs to be done.

protected Transferable contents (New)

The contents instance variable is the object currently on the clipboard; it was placed on the clipboard by owner. To retrieve the current contents, use the getContents() method.

Constructors

public Clipboard(String name) (New)

The constructor for Clipboard allows you to create a private clipboard named name. This clipboard is not accessible outside of your program and has no security constraints placed upon it.

Miscellaneous methods

public String getName() (New)

The getName() method fetches the clipboard's name. For private clipboards, this is the name given in the constructor. The name of the system clipboard is "System".

public synchronized Transferable getContents(Object requester) (New)

The getContents() method allows you to retrieve the current contents of the clipboard. This is the method you would call when the user selects Paste from a menu.

Once you have the Transferable data, you try to get the data in whatever flavor you want by calling the Transferable.getTransferData() method, possibly after calling Transferable.isDataFlavorSupported(). The requester represents the object that is requesting the clipboard's contents; it is usually just this, since the current object is making the request.

public synchronized void setContents(Transferable contents, ClipboardOwner owner) (New)

The setContents() method changes the contents of the clipboard to contents and changes the clipboard's owner to owner. You would call this method when the user selects Cut or Copy from a menu. The owner parameter represents the object that owns contents. This object must implement the ClipboardOwner interface; it will be notified by a call to lostOwnership() when something else is placed on the clipboard.


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