1 Reply Latest reply on Sep 6, 2006 7:58 PM by inlineblue

    How to prevent a NullPointer Exception?

    shyguychess Level 1

      Recently, I programmed the click() event for a Datagrid. However, this event fires when I scroll the datagrid which shouldn't be happening because I am not clicking the actual contents of the datagrid. Inside the click() event, I retrieve the contents of the itemselected but if the user is scrolling, there is no item selected and consequently, an error pops up stating that there is a null pointer for the click event. Is there any way to differentiate between scrolling and selecting a datagrid so this exception does not occur?

      Thanks in advance.
        • 1. Re: How to prevent a NullPointer Exception?
          inlineblue Level 1
          You're doing a couple of things wrong:

          1. You should be listening for the "change" event, not the click event. The change event fires when the grid's selection changes. The click event fires whenever you click anywhere in the grid component (even the scrollbar).

          2. When handling the event, you must check whether selectedItem is null. It's possible for the user to unselect an item, so you must compare against null first. eg:

          if (grid.selectedItem == null)
          return; //Do nothing