Java Swing, 2nd Edition

Chapter 24. Drag and Drop

Until the Java 2 platform hit the streets, Drag and Drop support (specifically, support for interacting with the native windowing system underneath the JVM) was lacking. The ability to let users drag a file from their file chooser into your application is almost a requirement of a modern, commercial user interface. The java.awt.dnd package gives you and your Java programs access to that support. You can now create applications that accept information dropped in from an outside source. You can also create Java programs that compile draggable information that you export to other applications. And, of course, you can add both the drop and drag capabilities to a single application to make its interface much richer and more intuitive.

“But wait!” you cry. “I recognize that package name. That’s an AWT package!” You’re right. Technically, Drag and Drop support is provided under the auspices of the AWT, not as a part of Swing. However, one driving force behind Swing is that it provides your application with a more mature, sophisticated user interface. Because Drag and Drop directly affects that maturity, we figured that you’d like to hear about it—even if it is not a part of Swing. And to try and hide that fact, we’ll be using Swing components in all of the examples. However, we should note for completeness that Drag and Drop support can be added just as easily to good, old-fashioned AWT components—they just don’t look as nice.