Component painted three times

Question

Hello
I have an AWT application containing a frame F1. This frame contains combos and buttons,
and another frame F2. Inside this frame F2, I have a TableBean component (GNU table for
AWT). When I show (only first time) frame F1, table component is painted three times. How can I
to dectect this component is already painted?. I don�t know how to use paint() or update().
Many thanks for your help.
tablaDatosListadoComercio = new tstuder.java.lib.component.table.Table(colDefs,linesComercio);
tablaDatosListadoComercio.getTitlebar().setBackground(java.awt.Color.blue);
tablaDatosListadoComercio.getTitlebar().setForeground(java.awt.Color.white);
tablaDatosListadoComercio.setSelectionMode(tstuder.java.lib.component.table.DataArea.SELECT_ONE);
tablaDatosListadoComercio.setHorizontalScrollMode(tstuder.java.lib.component.table.Table.HORIZONTAL_SCROLLBAR_OFF);
panelTablaLstComercio.add(tablaDatosListadoComercio);
((java.awt.CardLayout)getLayout()).show(this,"panelDatosListadoComercio");

Answer 1

I was talking with a co-worker about this kind of issue just yesterday - this isn't a simple problem at all.
Basically, you (the application programmer) don't have a lot of control over how many times your paint method is called. The Toolkit (AWT) is responsible for deciding when a component's paint method is called. You, as the application programmer, can hint to AWT that a component needs repainting by calling repaint.
Do not call paint yourself - AWT will call your paint method whenever it decides it wants to. It has in its own mind the state of everything, and which component needs to be repainted when. Controlling multiple repaints is a difficult problem for any GUI toolkit.
So here's a bit of theory which will hopefully enlighten, rather than confuse, you.
What you're doing when building an application is creating a bunch of objects that are meant to play together. The rules of the object behaviors are defined by the AWT (and Swing) Component classes. GUI applications are driven by the dispatch of events to them by the underlying system (in this case, Java, AWT and Swing). The bulk of the code being executed to do a GUI application is the underlying system (Java, AWT and Swing) since it's that underlying system that provides the basic framework for the application to exist in the first place.
- David