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What is supposed to be in the variable frame?
Where is the frame variable defined?
What class is the setJMenuBar() method in? Where is there an instance of that class inside of the MenuExample...

Where is line 87? Is it in the main() method? Move the code to the constructor where the variable: menuBar is available.

Hard to say without seeing the error message.
Please copy the full text of the error messages and paste it here.

Read the API doc for the JFrame class to see how to set its menu bar.
The add() method is for putting components in the content pane.