check
java.lang.String check(javax.swing.JComponent component)
Returns a non-null value if the check failed. Sometimes the return value
is used (for example, it is displayed as a tooltip for menu-items);
sometimes it is not (for example, toolbar buttons don't do anything with
the return value). An advanced use of an EnableCheck is simply to change
some property of a menu item (such as the text), as it is called when
menu items are displayed.
- Returns:
- an error message if the check failed, or null if the check
passed