You can retreive all the components from your panel with
getComponents() (it returns all components as Component array). Iterate through array with a loop and disable each component.
JTextArea is a specific component in this case. Actually, when you have it on your panel, what you get is not the text area, but scroll pane (automatically added when you add text area). So what
you should actually do is implement a recursive method, that can pick those components that are "deeper" (like the case here). Once you have them all (e.g. in a list), disable all of them.