Sobre NullPointerException

[TatianaC]

Olá,

Acabei de instalar o DNA – Discourse Network Analyzer e o executei pelo terminal. Abre normalmente, mas na hora de abrir um arquivo neste programa (extensão dna) ele não abre e aparece um erro no terminal que tem a ver com o que entendo é o NullPointerException.
Li alguns posts sobre como consertar isto, mas em todos já supõem que eu sei qual é o null. Não tenho ideia. Uso linux há 7 anos para as coisas básicas mas só agora estou me aventurando mais. Agradeço qualquer orientação!

Observação: Tenho instalado Ubuntu 15.10.

O erro que aparece no terminal é o seguinte:

Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
   at dna.OpenDatabaseDialog.loadDataAndDispose(OpenDatabaseDialog.java:275)
   at dna.OpenDatabaseDialog$3.actionPerformed(OpenDatabaseDialog.java:118)
   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
   at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
   at java.awt.Component.processMouseEvent(Component.java:6535)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
   at java.awt.Component.processEvent(Component.java:6300)
   at java.awt.Container.processEvent(Container.java:2236)
   at java.awt.Component.dispatchEventImpl(Component.java:4891)
   at java.awt.Container.dispatchEventImpl(Container.java:2294)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
   at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
   at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
   at java.awt.Container.dispatchEventImpl(Container.java:2280)
   at java.awt.Window.dispatchEventImpl(Window.java:2750)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
   at java.awt.EventQueue.access$500(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:709)
   at java.awt.EventQueue$3.run(EventQueue.java:703)
   at java.security.AccessController.doPrivileged(Native Method)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
   at java.awt.EventQueue$4.run(EventQueue.java:731)
   at java.awt.EventQueue$4.run(EventQueue.java:729)
   at java.security.AccessController.doPrivileged(Native Method)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
   at org.GNOME.Accessibility.AtkWrapper$5.dispatchEvent(AtkWrapper.java:697)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:109)
   at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:184)
   at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:229)
   at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:227)
   at java.security.AccessController.doPrivileged(Native Method)
   at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:227)
   at java.awt.Dialog.show(Dialog.java:1084)
   at java.awt.Component.show(Component.java:1673)
   at java.awt.Component.setVisible(Component.java:1625)
   at java.awt.Window.setVisible(Window.java:1014)
   at java.awt.Dialog.setVisible(Dialog.java:1005)
   at dna.OpenDatabaseDialog.<init>(OpenDatabaseDialog.java:258)
   at dna.Gui$MenuBar$2.actionPerformed(Gui.java:278)
   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
   at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
   at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
   at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
   at java.awt.Component.processMouseEvent(Component.java:6535)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
   at java.awt.Component.processEvent(Component.java:6300)
   at java.awt.Container.processEvent(Container.java:2236)
   at java.awt.Component.dispatchEventImpl(Component.java:4891)
   at java.awt.Container.dispatchEventImpl(Container.java:2294)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
   at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
   at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
   at java.awt.Container.dispatchEventImpl(Container.java:2280)
   at java.awt.Window.dispatchEventImpl(Window.java:2750)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
   at java.awt.EventQueue.access$500(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:709)
   at java.awt.EventQueue$3.run(EventQueue.java:703)
   at java.security.AccessController.doPrivileged(Native Method)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
   at java.awt.EventQueue$4.run(EventQueue.java:731)
   at java.awt.EventQueue$4.run(EventQueue.java:729)
   at java.security.AccessController.doPrivileged(Native Method)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
   at org.GNOME.Accessibility.AtkWrapper$5.dispatchEvent(AtkWrapper.java:697)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)