How to set number of collumns and rows in JTable after JTable object was created?

Hi, i have problem with JTable. I have to reuse JTable object after it
was previously created. I don't know how many rows it must contains at
the moment of creation, so I could not use default constructor
JTable(int col,int row). Is it possible to dynamically set size of the
jtable?
I need this jtable to present data from database querry. It each time
user clicks button "Show records" querry to database is made and
regarding how many rows it returns JTable object should be set to
proper number of rows.

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