Name: krT82822 Date: 03/06/2000


6 Mar 2000, eval1127@eng -- may be dupe/releative of # 4218515.

(see also 4218515, 4109910)

java version "1.3.0rc1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0rc1-T)
Java HotSpot(TM) Client VM (build 1.3.0rc1-S, mixed mode)


We have had NullPointerExceptions from DropTarget's addNotify()
method, when a JInternalFrame containing a DropTarget is made visible
by setVisible(true). This bug is probably part of the new
visibility model for JInternalFrames in 1.3 beta and 1.3RC1:


Exception in thread "main" java.lang.NullPointerException
        at java.awt.dnd.DropTarget.addNotify(DropTarget.java:431)
        at java.awt.Component.addNotify(Component.java:4046)
        at java.awt.Container.addNotify(Container.java:1548)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at javax.swing.JRootPane.addNotify(JRootPane.java:483)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at java.awt.Container.addNotify(Container.java:1555)
        at javax.swing.JComponent.addNotify(JComponent.java:4013)
        at javax.swing.JInternalFrame.show(JInternalFrame.java:1442)
        at java.awt.Component.show(Component.java:946)
        at java.awt.Component.setVisible(Component.java:903)
        at javax.swing.JComponent.setVisible(JComponent.java:1885)
        at icat.ictt.chat.ChatWindow.init(icat/ictt/chat/ChatWindow.java:408)
        at icat.ictt.chat.ChatWindow.<init>(icat/ictt/chat/ChatWindow.java:437)
        at icat.ictt.chat.ChatWindow.main(icat/ictt/chat/ChatWindow.java:462)



Here is the source, from DropTarget.java. The code at (1) is walking up
the tree hierarchy, looking for the Peer of the first heavyweight
component. Note that it does not check for a "not found," which
can happen for JInternalFrame. Also note that (2) is not considering
the possibility of a null, either.


    public void addNotify(ComponentPeer peer) {
/*
* FIX THIS FOR BETA4
*/

// java.security.AccessController.checkPermission(new
AWTPermission("setDTarget"));
if (peer == componentPeer) return;

componentPeer = peer;

(1)--> for (Component c = component; peer instanceof LightweightPeer; c =
c.getParent())
peer = c.getPeer();

try {
(2)--> ((DropTargetPeer)(nativePeer = peer)).addDropTarget(this);
} catch (ClassCastException cce) {
nativePeer = null;
// throw new InvalidDnDOperationException("No Native Peer support");
}
    }
(Review ID: 102116)
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