e639. determining when an item is no longer on the system clipboard.txt

这里面包含了一百多个JAVA源文件

When an item is set on the system clipboard, it is possible to be notified when that item is no longer on the clipboard. This is done by including a clipboard owner object when setting the item. 
    // This class serves as the clipboard owner.
    class MyClipboardOwner implements ClipboardOwner {
        // This method is called when this object is no longer
        // the owner of the item on the system clipboard.
        public void lostOwnership(Clipboard clipboard, Transferable contents) {
            // To retrieve the contents, see
            // e637 Getting and Setting Text on the System Clipboard
        }
    }

Here's some code that uses the clipboard owner: 
    // Create a clipboard owner
    ClipboardOwner owner = new MyClipboardOwner();
    
    // Set a string on the system clipboard and include the owner object
    StringSelection ss = new StringSelection("A String");
    Toolkit.getDefaultToolkit().getSystemClipboard().setContents(ss, owner);