is it possible to do a program to have a superclass of the GUI then having the logic and data under it without having much problems?? like

public class CreateGui extends JFrame{
JFrame frame;

private void initClass(String txt){

frame = new JFrame(txt);

}//initClass

public CreateGui(String text){
CreateGui guiClass = new CreateGui(text);
guiClass.initClass();
}//creatgui

}//class

anotherclass

public class DataClass extends CreateGui{

psvm(Strings[] args){
string text = "abcd";
CreateGui up = new CreateGui(text);
}//psvm

}//data class

or is it advisable to do it in reverse, because i was thinking of doing it to separate my gui class and my jdbc connection class

Yeah you can have
just import that class in the current one and create the object