title: Grayed out textfield unless checkbox ticked
body: <p>How, using <code>JTextField</code>, can I create my program to enable/disable a textfield depending on whether or not a checkbox is ticked?</p>
  
  <p>I have an option which, if checked, needs to take input. If not checked, I'd like the text field to remain grayed out with the user unable to enter text.</p>