Jfreechart how the data axis scale is set yourself

When we draw with Jfreechart, sometimes the scale on the data axis wants to define itself, such as the scale is 5, do not want to let Jfeechart automatic control, because its own control of the scale sometimes does not adapt to our needs. Numberaxis Numberaxis = (numberaxis) plot.getrangeaxis ();
Numberaxis. Setautotickunitselection (FALSE); Double unit=10d;//the length of the scale
Numbertickunit ntu= New Numbertickunit (unit);
Numberaxis. Settickunit (NTU); Dateaxis Xaxis = new Dateaxis (xName);
Xaxis.setrange (Start_time, end_time); Xaxis.setautotickunitselection (FALSE);
Xaxis.settickunit (New Datetickunit (datetickunit.minute,20)); Plot. Setdomainaxis (Xaxis);

<!--endfragment-->