1) Frame on top - - - 2) Quit

Question

I have 2 questions.
1) --------------------------------------------------------
I have 2 Classes in 2 different files. Class A and Class B.
Each one is with JFrame.
I am calling B from A like this : new B().show();
If "Window B" is running, I still have access to "Window A",
which I don't want.
So, If I run "Window B" then "Window A" should be in background,
untill I cancel "Window B".
How do I do this ?
2) --------------------------------------------------------
Regarding to the question above.
If I exit "Window B" like this : System.exit(0)
then "Window A" is also quit.
=> I dont want to exit "Window A"
If I "exit" "Window B" like this : this.setVisible(false)
=> I don't want to fill my memory, if I don't work with "Window B"
How do I exit "Window B"
- so that I still have "Window A"
- so that I don't fill my memory with data of "Window B"
Thank You
Aykut

Answer 1

1) does that meaning, I can not make JFrame window modal ?
2) If I change "Window B" from JFrame to JDialog,
than I can set it as modal ?
3) Do I need to change "Window A" also to JDialo ?
4) if I change "WIndow B"
from => class B extends java.awt.Frame {}
to => class B extends javax.swing.JDialog {}
do I need to change also a lot of other things ?