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Look at the API doc for the SwingWorker class. It has some examples there on how to use the class.
Java Platform SE 7

Sorry, I don't write code.

The method download() is not in scope where it is being referenced. The code that calls download needs a copy of the worker variable that is a reference to the class that contains the download()...

Please copy the full text of the error message and paste it here. It has important info about the error.

The code in post#11 has syntax errors and will NOT compile. Please post correct code.

I...

What error are you taking about? Can you explain?
Please copy the full text of the error message and paste it here. It has important info about the error.

When you create the worker class, pass it a reference to the class with the method you want to call.

I don't see where the methods and classes are from the snippets of code you have posted.
Can...

To call a method in a class, you need a reference to that class. Pass a reference to the class with the method you are trying to call to the class where you are trying to call it.

Can you make a small complete program the compiles, executes and shows the problem?