In order to support data transfer of custom data types, we need to implement the Transferable interface. Example 14-4 does that for the PolyLine class (a java.awt.Shape implementation) defined in Example 12-16. Transferable is a simple interface to implement, and this example is short. Note that the example also defines a DataFlavor for transferring PolyLine objects. Example 14-4. TransferablePolyLine.javapackage je3.datatransfer; import java.awt.datatransfer.*; import je3.graphics.PolyLine; /** * This class implements the Transferable interface for PolyLine objects. * It also defines a DataFlavor used to describe this data type. */ public class TransferablePolyLine implements Transferable { public static DataFlavor FLAVOR= new DataFlavor(PolyLine.class,"PolyLine"); static DataFlavor[ ] FLAVORS = new DataFlavor[ ] { FLAVOR }; PolyLine line; // This is the PolyLine we wrap. public TransferablePolyLine(PolyLine line) { this.line = line; } /** Return the supported flavor */ public DataFlavor[ ] getTransferDataFlavors( ) { return FLAVORS; } /** Check for the one flavor we support */ public boolean isDataFlavorSupported(DataFlavor f){return f.equals(FLAVOR);} /** Return the wrapped PolyLine, if the flavor is right */ public Object getTransferData(DataFlavor f) throws UnsupportedFlavorException { if (!f.equals(FLAVOR)) throw new UnsupportedFlavorException(f); return line; } } |