Exception in thread "AWT-EventQueue-0" java.lang.NullPointerExceptionat javax.swing.CellRendererPane.addImpl(CellRendererPane.java:85)at java.awt.Container.add(Container.java:365)at javax.swing.plaf.basic.BasicListUI.updateLayoutState(BasicListUI.java:1350)at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(BasicListUI.java:1299)at javax.swing.plaf.basic.BasicListUI.getPreferredSize(BasicListUI.java:566)at javax.swing.JComponent.getPreferredSize(JComponent.java:1632)at javax.swing.ScrollPaneLayout.layoutContainer(ScrollPaneLayout.java:769)at java.awt.Container.layout(Container.java:1421)at java.awt.Container.doLayout(Container.java:1410)at java.awt.Container.validateTree(Container.java:1507)at java.awt.Container.validateTree(Container.java:1513)at java.awt.Container.validateTree(Container.java:1513)at java.awt.Container.validateTree(Container.java:1513)at java.awt.Container.validateTree(Container.java:1513)at java.awt.Container.validate(Container.java:1480)at java.awt.Window.dispatchEventImpl(Window.java:2473)at java.awt.Component.dispatchEvent(Component.java:4413)at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)