I hope some one can tell me what i am doing wrong

here is what i am doing

i am getting the screen size, using the defaultToolkit,

and setting my JFrame size to the same size as that returned by that method(defaulttoolkit.getscreensize)

but my frame takes on a fixed size that is very small

i changed its size to double the screen size, but still it had the same original size,

i need help urgetnly please!!!

I am using Eclipse IDE. and i not at all familiar with it either!!!!
Please i would really appreciate someones help!!!!!!!!!!!!