JTable duplicate values in row

Question

I have a JTable populated with a custom DataModel (pasted below) and when I call the populate() method, it appears to populat

Answer 1

1) your TableModel is un_completed, I miss there lots or required methods for JTable's life_cycle, starting with TableHeader etc.

2) since there are lots of AbstactTableModels based on HashMap, I'd suggest to return arrays type implemented in API directly

Vector> data; 

String[][] or Object[][] 

instead of

ArrayList> data;

simple explanations is that XxxList returs column and Vector or String[] returns Row

3) I'd suggest to use DefaultTableModel directly then you'll never need to solve duplicates or missed column/row