Java SE (Java Platform, Standard Edition)

Hi guys,
I am now making a pente game.
I basically have a n by n JLabels filled a JPanel and set an image of a +.
When the label gets click, then the label simply reset the image to an image that shows a black or white stone.

Now I want to make it looks cool by flashing the stones if one player can form five in a row.

I was thinking to set images to a flashing gif image but that was my last option if i can find some built-in functions that can archieve the same goal.

Can anyone help with this?

Thanks,