How to center align all elements inside a jframe to center in java?

[Shammikit]

Im making a ATM enter PIN screen using java.i have written the code to make it appear full screen when i run it but all the other elements such as the jtextfield,labels and buttons are still at the top left corner of the screen.How can i get them all to the center of my screen? .

 

[rgd1101]

change the x(left) y(top) coordinates in code.