BlackBerry ObjectListField - list

Question

I am developing a BlackBerry project under JDE 4.6.1. The problem is that when adding an item to the list, a NullPointerException is thrown from method measureListRow
NPE callstack:
CustomerListField(ObjectListField).measureListRow(ListField, int, int)
CustomerListField(ListField).layout(int, int)
CustomerListField(ObjectListField).layout(int, int)
VList(Manager).layoutChild(Field, int, int)
Notes:
db_.getDataAccess() - database
getListCount - getting the number of items in the list
CustomerListItem - the structure of a list item
And the relevant code:
public class CustomerListField extends ObjectListField implements ListFieldCallback, ChangeListener {
private PagedDataFetcher dataFetcher = new CustomerListPagedDataFetcher();
…
public CustomerListField() {
try {
super.set(new Object[db_.getDataAccess().getListCount()]);
} catch (Throwable e) {
}
}
public void drawListRow(ListField listField, Graphics g, int index, int y,
int width) {
CustomerListItem currentRow = (CustomerListItem) get(listField, index);
…
}
public Object get(ListField list, int index) {
try {
return dataFetcher.getRowAtIndex(index);
} catch (Throwable e) {
return null;
}
}
// To obtain the data
public class CustomerListPagedDataFetcher extends PagedDataFetcher {
protected Vector get(int from, int to) throws Exception {
return DataAccess.getDataAccess().getLists(from, to);
}
}
/**
* layout for list
*/
final class VList extends VerticalFieldManager {
private final ObjectListField list;
int maxHeight = Display.getHeight() - getFont().getHeight() * 2 - 5;
VList(ObjectListField list) {
super(Manager.VERTICAL_SCROLLBAR | Manager.VERTICAL_SCROLL);
this.list = list;
}
public int getPreferredHeight() {
return 45 * list.getSize();
}
protected void sublayout(int width, int height) {
super.sublayout(width, height);
setExtent(width, maxHeight);
}
}

Answer 1

If you're getting a NullPointerException in measureRowList, the first place I'd look is the source of that method to see what null value is being dereferenced. It looks like you didn't include the source for that method though.