possible reasons are:
1) value is null
2) value is not a number (classcastexception)
3) value in a string not parsable (numberformatexception)

try to surrond with a try ... catch and see if is throwing an exception...

bye pat

2009/10/9 mingqiang yu <[email protected]>

> value is not an instance of String. It's an Object for the render which
> contains the grid data.
>
> What the sample is trying to do is to convert the value into formatted
> string: "$880" for display purpose. But for some reason, the formatting
> failed:
>
> NumberFormat nf = NumberFormat.getCurrencyFormat();
>
> return nf.format(((Number) value).doubleValue());
>
> It's very strange that I have this problem. It seems that no one else has
> encountered this problem.
>
> Thanks a lot for your help.
>
> M.Y.
>
>
> On Fri, Oct 9, 2009 at 11:47 AM, Patrizio De Michele 
> <[email protected]>wrote:
>
>> emh...maybe i wasn't clear...if (value instanceof String)  {
>> } else {
>>    value.toString();
>> }
>>
>>
>> 2009/10/9 mingqiang yu <[email protected]>
>>
>> The original data is populated just fine the grid. It's just that when I
>>> update the value in the grid, things go wrong. I tried to put this line to
>>> check if it's an instance of String:
>>>
>>>  Renderer renderer = new Renderer() {
>>>                 public String render(Object value, CellMetadata
>>> cellMetadata, Record record, int rowIndex, int colNum, Store store) {
>>>                     NumberFormat nf = NumberFormat.getCurrencyFormat();
>>>
>>>                     if ( nf.format(((Number) value).doubleValue())
>>> instanceof String ) {
>>>                         value = nf.format(((Number)
>>> value).doubleValue());
>>>                     }
>>>                    return value.toString(); // works fine
>>>                 }
>>> };
>>>
>>> But the problem is that the code was stuck at the checking point:
>>> if ( nf.format(((Number) value).doubleValue()) instanceof String ) {
>>>
>>> It seems that the Number casting to the value variable makes the program
>>> go crazy. But I really have no clue how I can fix it.
>>>
>>> Many thanks for your help!
>>>
>>> M.Y.
>>>
>>>
>>>
>>> On Fri, Oct 9, 2009 at 11:22 AM, Patrizio De Michele <
>>> [email protected]> wrote:
>>>
>>>> check if is an instance of number or instead is a string.....
>>>>
>>>>
>>>> 2009/10/9 my600080 <[email protected]>
>>>>
>>>>
>>>>> I tried to debug some more and here is what I found. The problem is in
>>>>> the line chart renderer. Here is the original code from gwtext 2.0.6
>>>>> sample LineChartSample.java code:
>>>>>
>>>>>            Renderer renderer = new Renderer() {
>>>>>                public String render(Object value, CellMetadata
>>>>> cellMetadata, Record record, int rowIndex, int colNum, Store store) {
>>>>>                    NumberFormat nf = NumberFormat.getCurrencyFormat
>>>>> ();
>>>>>                    return nf.format(((Number) value).doubleValue());
>>>>>               }
>>>>>            };
>>>>>
>>>>> For this piece of code, if I update the value in the line chart data
>>>>> grid, the value will not get updated and so the chart is not
>>>>> refreshed.
>>>>>
>>>>> If I change the above as following:
>>>>>
>>>>>            Renderer renderer = new Renderer() {
>>>>>                public String render(Object value, CellMetadata
>>>>> cellMetadata, Record record, int rowIndex, int colNum, Store store) {
>>>>>                    return value.toString();
>>>>>               }
>>>>>            };
>>>>>
>>>>>
>>>>> Then the line chart data grid update works just fine (of course, it's
>>>>> not formatted any more) and so the chart is refreshed correctly with
>>>>> the new data.
>>>>>
>>>>> Do you know what the problem might be? Is it possible that I cannot
>>>>> cast the value object inside the renderer?
>>>>>
>>>>> Your help is highly appreciated!
>>>>>
>>>>> M.Y.
>>>>>
>>>>> On Oct 7, 4:27 pm, my600080 <[email protected]> wrote:
>>>>> > I'm using Eclipse Galileo, GWT 1.7 and GWT-EXT 2.0.6. I copied the
>>>>> > Charts samples into my workspace. Everything works ok except that
>>>>> when
>>>>> > I tried to update the values in the Grid for any of the charts, the
>>>>> > change reverses back right away to the old value. Is this something
>>>>> > that anyone else has experienced as well? Or is it just me? Thanks!
>>>>> >
>>>>> > M.Y.
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>>
>
> >
>

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