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Error:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at leapp.BehemothSelectGUI.cmbMothHeadActionPerformed(BehemothSelectGUI.java:141) at leapp.BehemothSelectGUI.access$100(BehemothSelectGUI.java:12) at leapp.BehemothSelectGUI$2.actionPerformed(BehemothSelectGUI.java:61) at javax.swing.JComboBox.fireActionEvent(JComboBox.java:1258) at javax.swing.JComboBox.contentsChanged(JComboBox.java:1332) at javax.swing.JComboBox.intervalRemoved(JComboBox.java:1352) at javax.swing.AbstractListModel.fireIntervalRemoved(AbstractListModel.java:179) at javax.swing.DefaultComboBoxModel.removeAllElements(DefaultComboBoxModel.java:174) at javax.swing.JComboBox.removeAllItems(JComboBox.java:771) at leapp.Populate.cmbPop(Populate.java:52) at leapp.BehemothSelectGUI.(BehemothSelectGUI.java:25) at leapp.HeroSelectGUI.btnChooseMothActionPerformed(HeroSelectGUI.java:170) at leapp.HeroSelectGUI.access$000(HeroSelectGUI.java:14) at leapp.HeroSelectGUI$1.actionPerformed(HeroSelectGUI.java:78) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022) at javax.swing.AbstractButton$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:6533) at javax.swing.JComponent.processMouseEvent(JComponent.java:3324) at java.awt.Component.processEvent(Component.java:6298) at java.awt.Container.processEvent(Container.java:2236) at java.awt.Component.dispatchEventImpl(Component.java:4889) at java.awt.Container.dispatchEventImpl(Container.java:2294) at java.awt.Component.dispatchEvent(Component.java:4711) 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:2746) at java.awt.Component.dispatchEvent(Component.java:4711) 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 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) BUILD SUCCESSFUL (total time: 7 seconds)

I'm trying to get a selected item from a combobox that a user chose and take the item and store its database value like "HitPoints" in a integer.

private void cmbMothHeadActionPerformed(java.awt.event.ActionEvent evt) {                                            
    String data[][] = db.selectAll("tblBehemoth");
    int selected = (int) cmbMothHead.getSelectedItem();
    String HP = data[selected][2]; //First [] = Row number // Second [] = Col Name
    System.out.println(HP);
}

All data is stored in a database and Hitpoints is a column name

Hovercraft Full Of Eels
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Stuart Campbell
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  • Which line is `BehemothSelectGUI.java:141`, the one indicated by the stacktrace? – Hovercraft Full Of Eels Aug 24 '17 at 14:47
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    Also, the heuristic for debugging a NullPointerException is almost always the same: You should critically read your exception's stacktrace to find the line of code at fault, the line that throws the exception, and then inspect that line carefully, find out which variable is null, and then trace back into your code to see why. You will run into these again and again, trust me. In the future, please search on the subject before posting, since this is too common a problem to post yet another NPE question. – Hovercraft Full Of Eels Aug 24 '17 at 14:47
  • @HovercraftFullOfEels int selected = (int) cmbMothHead.getSelectedItem(); – Stuart Campbell Aug 24 '17 at 14:49
  • So now you know that the `cmbMothHead` variable is null at this location (scope) and time when you are trying to call a method off of it. Look through your code (which only **you** have) to find out *why*. – Hovercraft Full Of Eels Aug 24 '17 at 14:51
  • @HovercraftFullOfEels Thanks, but now I get a Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer – Stuart Campbell Aug 24 '17 at 15:00
  • This is a new and unrelated problem, and you should try to debug it. None of us can solve it based on your simply posting the exception message. Search on this error on this site and others, see how others have dealt with it, ***carefully read the line of code that is causing the problem, and try to debug it***. Only if you're still stuck, ask a new question on this site, showing your [mcve] code, showing the concrete results of your search efforts, and showing your specific question. – Hovercraft Full Of Eels Aug 24 '17 at 15:03

0 Answers0