Java: Where to declare components
Components are typically declared in one of several places:
Field variables
Some components should be declared as field variables (instance variables, member variables).
This is the appropriate place to declare components which
must be referenced after the interface is constructed.
Typically these are text fields or text areas, check boxes, etc.
Those components whose values must be gotten or set.
Local variables
Local variables should be used for components which are
never referenced after the interface is constructed. Typically
these are panels for holding components, buttons (whose interaction
is thru their listeners), ... Local variables disappear when the
method they are in returns, but the component will continue to
exist if it has been added to the interface.
Anonymous
Anonymous creation is typical with labels, which can be
created and added in one step and never assigned to a variable.
Of course, if the appearance (font, alignment, ...) must be
changed, then they should be put in a local variable. Some
programs use labels for output (not a good idea), and in this
case they should be field variables. Example
content.add(new JLabel("Look at this"));