how to Clear the previous inputs before displaying to jtable

Question

Sorry for my English...

So I made a simple program for book inventory that displays the inputted strings in a jtable so i have a radiobutton that only disable certain fields which is Jdatechooser and one jtextfield for name, and enables them when the specific radiobutton is clicked. So here's the scenario, when I clicked a radiobutton which disables the certain fields and left with only the ones that is needed the most then when the time i add them to j table it displays correctly with having two blanks in two columns. it's also same when I choose a Radiobutton that enables the two previously disabled fields which also displays correctly have inputs in the two columns but here comes the problem when i clicked back the radiobutton and inputted the necessary fields and when it is displayed in jtable the previous input also displays which i intended to be blank i've tried setText but didnt worked... so the question is do you know how to clear that or make it blank every time i click the radiobutton that disable two fields?

that is the best explaination i can ever give can you help me???

here is the photo (the circled part is supposed to be blank)