Re: how to delete a JList element

From:

thufir <hawat.thufir@gmail.com>

Newsgroups:

comp.lang.java.help

Date:

Sat, 21 Jun 2008 21:23:50 GMT

Message-ID:

<Gje7k.23023$Jx.19384@pd7urf1no>

On Sat, 21 Jun 2008 21:01:21 +0000, thufir wrote:

This seems to give a NullPointerException, as below, because the backing
collection is a DefaultListModel:

I got basically the same result when trying to change the backing
DefaultListModel directly:

thufir@arrakis:~/bcit-comp2611-project2$
thufir@arrakis:~/bcit-comp2611-project2$ head src/a00720398/view/
NewJFrame.java -n 481 | tail -n 10

   private void deleteGuestActionPerformed(java.awt.event.ActionEvent
evt)//GEN-FIRST:event_deleteGuestActionPerformed
   {//GEN-HEADEREND:event_deleteGuestActionPerformed
      int i =guestList.getSelectedIndex();
      BedAndBreakfast bnb = BedAndBreakfast.getInstance(); //the
"database"
      System.out.println("delete guest \t" + i + bnb.getGuests().get(i));
      //((DefaultListModel)(guestList.getModel())).removeElementAt(i);
      bnb.getGuests().removeElementAt(i);
   }//GEN-LAST:event_deleteGuestActionPerformed

thufir@arrakis:~/bcit-comp2611-project2$

it runs and, apparently, works but there are still run time
java.lang.NullPointerException errors.

I can change bnb.getGuests() to return a Map, but then HashMap doesn't
convert nicely to an array...

I assume that the NullPointerException is because DefaultListModel
doesn't nicely handle a change of index?

-Thufir

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