JDK-4805978 : ToolTipManager NullPointerException in 1.4.1
  • Type: Bug
  • Component: client-libs
  • Sub-Component: javax.swing
  • Affected Version: 1.4.1
  • Priority: P4
  • Status: Closed
  • Resolution: Not an Issue
  • OS: windows_2000
  • CPU: x86
  • Submitted: 2003-01-21
  • Updated: 2003-01-23
  • Resolved: 2003-01-23
Related Reports
Relates :  
JDK-6337516 - NullPointerException in ToolTipManager on mouseExit
Description

Name: jk109818			Date: 01/21/2003


FULL PRODUCT VERSION :
java version "1.4.1_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_01-b01)
Java HotSpot(TM) Client VM (build 1.4.1_01-b01, mixed mode)

FULL OPERATING SYSTEM VERSION :  Microsoft Windows 2000
[Version 5.00.2195]


A DESCRIPTION OF THE PROBLEM :
Null pointer exception in ToolTipManager (version 1.4.1).

In a JPanel I am displaying a complex drawing.  As the
mouse moves over the drawing different elements in the
drawing may display a tooltip.  This is done by overriding
getToolTipText(MouseEvent e) in the display.  getToolTipText
() returns a String when the mouse is over a tooltip-
enabled element and null otherwise.  The exception below
occurs when not over a tooltip-enabled element.

java.lang.NullPointerException

	at javax.swing.ToolTipManager.initiateToolTip
(ToolTipManager.java:497)

	at javax.swing.ToolTipManager.mouseEntered
(ToolTipManager.java:458)

	at java.awt.AWTEventMulticaster.mouseEntered
(AWTEventMulticaster.java:238)

	at java.awt.AWTEventMulticaster.mouseEntered
(AWTEventMulticaster.java:237)

	at java.awt.Component.processMouseEvent
(Component.java:5102)

	at java.awt.Component.processEvent
(Component.java:4890)

	at java.awt.Container.processEvent
(Container.java:1566)

	at java.awt.Component.dispatchEventImpl
(Component.java:3598)

	at java.awt.Container.dispatchEventImpl
(Container.java:1623)

	at java.awt.Component.dispatchEvent
(Component.java:3439)

	at java.awt.LightweightDispatcher.retargetMouseEvent
(Container.java:3450)

	at
java.awt.LightweightDispatcher.trackMouseEnterExit
(Container.java:3290)

	at java.awt.LightweightDispatcher.processMouseEvent
(Container.java:3147)

	at java.awt.LightweightDispatcher.dispatchEvent
(Container.java:3095)

	at java.awt.Container.dispatchEventImpl
(Container.java:1609)

	at java.awt.Window.dispatchEventImpl
(Window.java:1585)

	at java.awt.Component.dispatchEvent
(Component.java:3439)

	at java.awt.EventQueue.dispatchEvent
(EventQueue.java:450)

	at
java.awt.EventDispatchThread.pumpOneEventForHierarchy
(EventDispatchThread.java:197)

	at
java.awt.EventDispatchThread.pumpEventsForHierarchy
(EventDispatchThread.java:150)

	at java.awt.EventDispatchThread.pumpEvents
(EventDispatchThread.java:144)

	at java.awt.EventDispatchThread.pumpEvents
(EventDispatchThread.java:136)

	at java.awt.EventDispatchThread.run
(EventDispatchThread.java:99)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1.  In a JPanel, draw several lines and a few circles.
2.  Allow circles to have tooltips, for lines no tooltip
3.  Moving mouse around should show this problem.

EXPECTED VERSUS ACTUAL BEHAVIOR :
No null pointer exceptions from ToolTipManager

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NullPointerException

	at javax.swing.ToolTipManager.initiateToolTip(ToolTipManager.java:497)

	at javax.swing.ToolTipManager.mouseEntered(ToolTipManager.java:458)

	at java.awt.AWTEventMulticaster.mouseEntered
(AWTEventMulticaster.java:238)

	at java.awt.AWTEventMulticaster.mouseEntered
(AWTEventMulticaster.java:237)

	at java.awt.Component.processMouseEvent(Component.java:5102)

	at java.awt.Component.processEvent(Component.java:4890)

	at java.awt.Container.processEvent(Container.java:1566)

	at java.awt.Component.dispatchEventImpl(Component.java:3598)

	at java.awt.Container.dispatchEventImpl(Container.java:1623)

	at java.awt.Component.dispatchEvent(Component.java:3439)

	at java.awt.LightweightDispatcher.retargetMouseEvent
(Container.java:3450)

	at java.awt.LightweightDispatcher.trackMouseEnterExit
(Container.java:3290)

	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3147)

	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3095)

	at java.awt.Container.dispatchEventImpl(Container.java:1609)

	at java.awt.Window.dispatchEventImpl(Window.java:1585)

	at java.awt.Component.dispatchEvent(Component.java:3439)

	at java.awt.EventQueue.dispatchEvent(EventQueue.java:450)

	at java.awt.EventDispatchThread.pumpOneEventForHierarchy
(EventDispatchThread.java:197)

	at java.awt.EventDispatchThread.pumpEventsForHierarchy
(EventDispatchThread.java:150)

	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)

	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)

	at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)



REPRODUCIBILITY :
This bug can be reproduced often.

---------- BEGIN SOURCE ----------
public String getToolTipText(MouseEvent e) overridden in the display.
---------- END SOURCE ----------

CUSTOMER WORKAROUND :
Returning the String "" helps, but screen still flashes
when I move mouse over it.
(Review ID: 179296) 
======================================================================
Comments
EVALUATION The method JComponent.getToolTipText() should not return null. The application should use setToolTipText(null) to turn off tooltips instead of overriding the get method. If the method still needs to be overriden, the app should call ToolTipManager.unregisterComponent(panel) when it doesn't want to display a tooltip. This way the get method is not called. Closing as not a bug. ###@###.### 2003-01-22
22-01-2003