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getContentPane is a method, but you are writing code that treats it as a variable. Go back to the one line of code I posted and see how your code differs from it.

edit The earlier method call in...

frame.getContentPane().setBackground(...)
db

You're setting the background of a JFrame. But the background of a JFrame is covered by its contentPane, which is by default opaque. You should be setting the background of the contentPane.

Oh,...