java.lang.NullPointerException when scrolling in JComboBox
Hi everybody,
I use a JComboBox in my application. If I scroll it a NullPointerException is thrown:
java.lang.NullPointerException
at javax.swing.BufferStrategyPaintManager.flushAccumulatedRegion(BufferStrategyPaintManager.java:406)
at javax.swing.BufferStrategyPaintManager.copyArea(BufferStrategyPaintManager.java:334)
at javax.swing.RepaintManager.copyArea(RepaintManager.java:1143)
at javax.swing.JViewport.blitDoubleBuffered(JViewport.java:1604)
at javax.swing.JViewport.windowBlitPaint(JViewport.java:1573)
at javax.swing.JViewport.setViewPosition(JViewport.java:1118)
at javax.swing.plaf.basic.BasicScrollPaneUI$Handler.vsbStateChanged(BasicScrollPaneUI.java:1027)
at javax.swing.plaf.basic.BasicScrollPaneUI$Handler.stateChanged(BasicScrollPaneUI.java:1016)
at javax.swing.DefaultBoundedRangeModel.fireStateChanged(DefaultBoundedRangeModel.java:348)
at javax.swing.DefaultBoundedRangeModel.setRangeProperties(DefaultBoundedRangeModel.java:285)
at javax.swing.DefaultBoundedRangeModel.setValue(DefaultBoundedRangeModel.java:151)
at javax.swing.JScrollBar.setValue(JScrollBar.java:446)
at javax.swing.plaf.basic.BasicScrollPaneUI$Handler.mouseWheelMoved(BasicScrollPaneUI.java:962)
at java.awt.Component.processMouseWheelEvent(Component.java:6126)
at java.awt.Component.processEvent(Component.java:5810)
at java.awt.Container.processEvent(Container.java:2058)
at java.awt.Component.dispatchEventImpl(Component.java:4410)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchMouseWheelToAncestor(Component.java:4555)
at java.awt.Component.dispatchEventImpl(Component.java:4296)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4015)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
at java.awt.Container.dispatchEventImpl(Container.java:2102)
at java.awt.Window.dispatchEventImpl(Window.java:2429)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
This is the code I execute:
publicstaticvoid test()
{
Object[] items =new Object[10];
items[0] = 0;
items[1] = 1;
items[2] = 2;
items[3] = 3;
items[4] = 4;
items[5] = 5;
items[6] = 6;
items[7] = 7;
items[8] = 8;
items[9] = 9;
JFrame frame =new JFrame("Test frame");
JPanel panel =new JPanel();
panel.add(new JLabel("Combobox:"));
panel.add(new JComboBox(items));
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
The weird thing is that if I execute this piece of code outside my program, in a test class, everything goes fine. I am not sure how this is possible.
Best regards,
Jethro Borsje
