JDK-4287795 : Would like Clipboard.isDataFlavorSupported() method
  • Type: Enhancement
  • Component: client-libs
  • Sub-Component: java.awt
  • Affected Version: 1.2.2
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 1999-11-04
  • Updated: 2017-05-16
  • Resolved: 2003-07-25
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Other
5.0 tigerFixed
Related Reports
Relates :  
JDK-6255835 - TransferHandler.pasteAction should not use Clipboard.getContents() for performance reasons
Relates :  
JDK-4790833 - Memory usage shoots way up using Clipboard.getContents()
Relates :  
JDK-4259272 - Support Notifications of Clipboard Contents Changes
Description

Name: krT82822			Date: 11/03/99


java version "1.2.2"
HotSpot VM (1.0.1, mixed mode, build c)
Currently, to see if the Paste menu item in a Java application should be
enabled, you must do Clipboard.getContents(), and if it doesn't return null,
see if the returned Transferable has a compatible datatype by calling
Transferable.isDataFlavorSupported(). However, getContents() can take a while
if the clipboard contents is large (e.g. many pages of text).

It isn't actually necessary to retrieve the contents of the clipboard to enable
the menu item, only to see if the clipboard contains appropriate data. A method
Clipboard.isDataFlavorSupported() would be very helpful if it were faster than
Clipboard.getContents().
(Review ID: 97424) 
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Comments
CONVERTED DATA BugTraq+ Release Management Values COMMIT TO FIX: tiger FIXED IN: tiger INTEGRATED IN: tiger tiger-b13
24-08-2004
EVALUATION What the submitter is really asking for the Clipboard to generate data on demand, and in the desired DataFlavor, much like the DnD subsystem works. This is a much needed addition to the API. Committing to merlin for now. david.mendenhall@eng 1999-12-14 In merlin, we didn't have time to implement delayed data fetch, although we did at least implement delayed rendering. Committing to tiger. david.mendenhall@east 2000-12-14 Name: agR10216 Date: 06/27/2003 The following CCC request was approved. 4287795: Would like Clipboard.isDataFlavorSupported() method Release: Tiger Type: enhancement Problem The related problems are described in the RFE 4287795 [Would like Clipboard.isDataFlavorSupported() method] and in the bug 4790833 [Memory usage shoots way up using Clipboard.getContents()]. The only way to know something about contents of a clipboard using the present API is to call java.awt.datatransfer.Clipboard.getContents() and examine the Transferable returned. For system clipboard getContents() retrieves whole contents of the clipboard, it retrieves data in each supported format, so that Transferable returned is independent of current contents of the system clipboard later on. Thus, if one wants only to check whether data in a particular DataFlavor is available on the clipboard or to get data in a single DataFlavor, using getContents() is inefficient: it unnecessarily consumes a lot of memory and slackens performance. Solution Add 3 methods to the class java.awt.datatransfer.Clipboard, which allow to get DataFlavors currently available on the clipboard, check whether a particular DataFlavor is available, and get data in a particular DataFlavor. Interface summary exported external method java.awt.datatransfer.Clipboard.getAvailableDataFlavors isDataFlavorAvailable getData Specification java.awt.datatransfer.Clipboard: /** * Returns an array of <code>DataFlavor</code>s in which the current * contents of this clipboard can be provided. If there are no * <code>DataFlavor</code>s available, this method returns a zero-length * array. * * @return an array of <code>DataFlavor</code>s in which the current * contents of this clipboard can be provided * * @throws IllegalStateException if this clipboard is currently unavailable * * @since 1.5 */ public DataFlavor[] getAvailableDataFlavors() /** * Returns whether or not the current contents of this clipboard can be * provided in the specified <code>DataFlavor</code>. * * @param flavor the requested <code>DataFlavor</code> for the contents * * @return <code>true</code> if the current contents of this clipboard * can be provided in the specified <code>DataFlavor</code>; * <code>false</code> otherwise * * @throws NullPointerException if <code>flavor</code> is <code>null</code> * @throws IllegalStateException if this clipboard is currently unavailable * * @since 1.5 */ public boolean isDataFlavorAvailable(DataFlavor flavor) /** * Returns an object representing the current contents of this clipboard * in the specified <code>DataFlavor</code>. * The class of the object returned is defined by the representation * class of <code>flavor</code>. * * @param flavor the requested <code>DataFlavor</code> for the contents * * @return an object representing the current contents of this clipboard * in the specified <code>DataFlavor</code> * * @throws NullPointerException if <code>flavor</code> is <code>null</code> * @throws IllegalStateException if this clipboard is currently unavailable * @throws UnsupportedFlavorException if the requested <code>DataFlavor</code> * is not available * @throws IOException if the data in the requested <code>DataFlavor</code> * can not be retrieved * * @see DataFlavor#getRepresentationClass * * @since 1.5 */ public Object getData(DataFlavor flavor) throws UnsupportedFlavorException, IOException Compatibility risk: minimal ###@###.### 2003-06-27 ======================================================================
27-06-2003
SUGGESTED FIX Name: agR10216 Date: 06/27/2003 Implement the new methods described in the evaluation for private and system clipboards. ###@###.### 2003-06-27 ======================================================================
27-06-2003