Memory leak when refreshing table models

Question

Hi,
I have a memory leak in a GUI app, and i have traced the problem down to some JTables I have which display data from a database (I used Netbeans profiler to look at the number of objects created for different classes, and there are a large number of classes like com.mysql.jdbc.ResultSet, com.mysql.jdbc.Statement, com.mysql.jdbc.Field[] accumulating, aswell as lots of byte[] and char[] arrays). The allocation stack traces for these objects seem to point to my table models where I do a lot of database lookups to create the model.
Every time I am refreshing the tables, the Heap Space increases by a few MegaBytes, and a load of objects get created and retained. After refreshing the tables a number of times, the heap eventually gets filled and I get OutOfMemory error.
The problem is I don't understand how this is happening - when the tables are refreshed, the code I use is something like this:
setModel(new MyTableModel());
So theoretically each time I refresh, the old model should be garbage collected (because setting the new model means there are no references to the old model), but I get the feeling that all the models are accumulating in the heap and not being collected. I dont understand why this could be - I was wondering if anyone had any ideas? (PS My table models dont use any static fields)
Cheers,
james

Answer 1

Hi JacobsB,
The reason I'm setting new models (which I dont normally do) is that each time the table is refreshed, the number and type of columns may change. Since altering the column model is quite complicated (there is no convenient removeColumn() method of any of the standard model classes) and involves messing around with the column model, which ends up screwing up the whole model (e.g. column renderers, column count, column class etc.) I decided it was actually easier to just create a new model instead! Is there a way to alter the column structure another way?
later,
James