First of all, the data Vector you are using is defined inside methodOne so the same data is not accesible via methodTwo.
Secondly it is not because there is data being added to data in a tablemodel that the table will refresh, you have to call one of the methods that trigger an refresh event in the gui, normally one calls the method fireTableChanged on the tablemodel after you added data.
Thridly: there is an interesting library called GlazedLists that handles a lot of these things automatically !