Category: Software development

drop down box
Clear a list for selectionOneMenu every time, got burned by this in a “page number” drop down for Richfaces data scroller. And some other places.

Use validator
keep in mind it will overwrite the required = “true”, if the user does not select a valid value from drop down, it will give error message during Save method.

Assign 0 to “–select–” ?
Yes or no. Add 0 means 0 is a selectable option, so if one wants to enforce user to select something using required=”true”, it will pass this check. Thus comes in the validator, in which one can say “0” is not valid.

Page number for data scroller
1) t:saveState if we can not have session scope for dataBean;
2) the drop down tip above;
3) When “adding or deleting rows” and it cause the total number of pages changes, make sure set the correct page number in the “action” (save) methods.

The following was written more than a year ago…

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Got opportunity to work on those two technologies recently due to job change. Had some gotchas as I transform from C++, CAD programming to this new program paradigm.

Data problem vs. coding error
In CAD world, sometimes there is problem with the data (CAD file) itself. But most of the time I focus my effort debugging the coding error in my own code, not trying to debugging the data itself. In Oracle/Database world, I found it more often that the data itself could complicate problem. Because the relational database has relationship between table, sometimes we can not add/delete/update table at will due to dependencies (data integrity). This also bring about the second topic I want to discuss.

C++ vs. Java
Java is not as flexible as C++. For instance, how to pass data back from a function, so far I found one way: using the return data. In C++, I used the pointer and reference quite a bit. The wiring of inheritance and interface (implementation) could also got a bit complicated: basically one needs to draw the relationships on a paper to better understand all those.

Eclipse vs. Visual Studio
Eclipse (the free Java IDE) is quite powerful, actually. It’s also highly configurable, with so many plug-ins, e.g., this subclipse integrates Eclipse with Subversion. I remember I could not do such things inside Visual Studio (for Perforce).