14.5 A Transferable Shape

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.java

package 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;
    }
}