Sure, you can read the JTable API and follow the link to the Swing tutorial on "How to Use Tables" for an example of a custom renderer. You can try to create your own.
If you need further help then you need to create a
SSCCE (Short, Self Contained, Compilable and Executable, Example Program), that demonstrates the incorrect behaviour.
Don't forget to use the Code Formatting Tags so the posted code retains its original formatting. That is done by selecting the code and then clicking on the "Code" button above the question input area.