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A couple of possiblities:

Either implement your own Dataset wrapper that returns only the N latest points even when having more than N.
Or alternatively implement zooming and/or scrolling to your graph so that the view only shows the N latest but you can scroll back to view the older data.

I don't fully understand what your X-axis is (some kind of time, perhaps?), but here is a suggestion: use just the one series: -add value (x1, 5) -add value (x2, 0) -add value(x2, null) -add value(x2, 360) -add value(x3, 355) So you would compute the change from 0 to 360 before adding the data to th...

If you change your chart from CategoryChart to XYChart then you would get connected lines.
I am not familiar with CategoryChart so I do now know if it is also possible with that.

You might want to take a look at TooltipChartPanel which has basic framework for generating the tooltips on-the-fly when needed (instead of creating all tooltip entities before rendering). It had also a parameter for defining the hotspot radius. See http://www.jfree.org/phpBB2/viewtopic.php?p=69588#...

You should probably call JFreeChart.setNotify(false) before your loop, add the new items directly to the existing dataset, and then after the loop call JFreeChart. setNotify(true) . Now each new element forces a redraw of the whole chart (with the increasingly big dataset) via notifications. By disa...

Adding a null value causes a gap in the line.

...
xy1.add(30, 64);
xy1.add(40,null);
xy1.add(70, 80);
...

If you are going to show only positive Y-values why not use the NumberAxis method for your Y-axis? This way the zoom out will not slip into negative range.

It is possible, you need to generate the image map for the image with the API.

Unfortunately I am not familiar with that API and cannot help you further but I am certain that if you search the forum you can find the answer.

What are you trying to achieve? Now you have summarized the database values into one datapoint per month. I am guessing that you have only date values for March and April in the database - hence the two datapoints in the graph. Apparently this is not what you wanted, so please either re-think your l...

You are adding the series twice into the dataset.

First in the constructor: and immediately again: Remove the second entry and you should be fine.

Perhaps ClusteredXYBarRenderer is what you need:

http://www.jfree.org/jfreechart/api/jav ... derer.html

Which version of JFreeChart are you using? There was a problem in the initial versions where this happened but it should be fixed now.

I cannot remember on the top of my head the broken version nor where it started to work. You should be able to find similar threads with the Search, though...

You don't have to have entity collection. Please take a look at the TooltipChartPanel by RoyW , it has basic framework for generating the tooltips on-the-fly when needed. It maps the mouse coordinates to X,Y index and scans the datasets for matching datapoints. See http://www.jfree.org/phpBB2/viewto...

Could it be that your JFreeChart is version 1.0.10 or older?
See http://www.jfree.org/phpBB2/viewtopic.p ... 510#p73510

If the answer is yes, either update your JFreeChart libraries or alternatively do this

If you were to use XYLine chart (and of course XYSeries for the data), then the lines would have no gaps.
Mind here that I have absolutely no knowledge of Category charts nor Jasper reports, so maybe someone has a solution for a Category chart.