|
Drag and Drop: New Data Transfer Capabilities in the JavaTM 2 Platform, Standard Edition (J2SETM), version 1.4(2) One of the new capabilities now available is improved data transfer support within and between applications. Data transfer includes two tasks: cut, copy, and paste Access to the user or system clipboard and drag-and-drop support. Neither of these features is totally new to the standard library set. However, what you can do with them now in the 1.4 release and how you interact with the features has totally changed. Older programs, designed for the earlier data transfer mechanism, will continue to work fine, but in many cases the source code for the task can be simplified considerably. Before looking into how to use the drag-and-drop capabilities of the J2SE, version 1.4 release, there is some background information you need to understand. ClipboardsFirst off is a look at clipboards. If you aren't familiar with what a clipboard is, it is a memory area for storing information in support of cut, copy, and paste operations. For instance, when you are using a Word processor and cut a piece of text to place the text elsewhere in the document, the text that was cut is saved within the clipboard. When it becomes time to paste the text, the paste operation reads what is on the clipboard and pastes it into the document. There are actually multiple clipboards available. There is one global clipboard that all applications have Access to, and private clipboards that can be limited in scope to within a single application. By utilizing a private clipboard in an application, you don't copy into system memory what goes onto the system clipboard. Instead, it stays within the application's memory space. Transferable ObjectsWhile you now know what a clipboard is, you haven't learned anything about the objects that can go into the clipboard. With the Java platform, objects that can be placed within a clipboard must implement the Transferable interface, found in the Java.awt.datatransfer package. public interface Transferable {public Object getTransferData(DataFlavor flavor)throws UnsupportedFlavorException, IOException;public DataFlavor[] getTransferDataFlavors();public boolean isDataFlavorSupported(DataFlavorflavor);}
| 
