How can I change a var in class C from class B if C and B are created in A?

Question

Hi!
I have a little problem. It´s not really a Swing problem as you may believe by reading below, it´s about object creation.
I have a JFrame class called TransactionDialog. The TransactionDialog contains a JPanel with a CardLayout.
The CardLayout contains two components:
1) JPanelStep1 (an own class that extends JPanel)
2) JPanelStep2 (an own class that extends JPanel)
I want a variable in JPanelStep2 to depend on what the user does in JPanelStep1.
The question:
Both the JPanelStep1 and JPanelStep2 objects are created in the TransactionDialog class. How can I call the JPanelStep2 object (which is created in TransactionDialog ) from JPanelStep1 if JPanelStep1 has to be created before JPanelStep2 in the TransactionDialog class?

Answer 1

Jacobs has the right idea.
If this variable is part of the SWING display, you can do it the quick and easy way by passing that display object to JPanelStep1 and allowing that panel to mutate the value.
For instance:
JPanelStep1 step1 = new JPanelStep1();
JPanelStep2 step2 = new JPanelStep2();
step1.setDependent(step2.getDependent());
And the methods would be for example:
void setDependent(JTextField field) {
this.field = field;
JTextField getDependent() {
return field;
And whenever the user interacts with JPanelStep1 and you want to alter the text as it displays in JPanelStep2 you just make a call in JPanelStep1 to:
field.setText(updatedText);
Do not forget though that if you do not have your MDT squared away, the update might not occur immediately, without calling to your JFrame or throwing a thread on the MDT with invokeAndWait()