Error: javax.swing.AbstractButton cannot be applied to...

Hi, iv written a program which has a JtabbedPane GUI but the problem is on one of my tabs i have a JPanel called panel1. on panel1 i have a button called addButton now i add this button onto my panel and my panel onto the tab using the following code:

Code:

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panel1.add(addButton);
tabbedPane.addTab("New Booking", null, panel1, "First Panel");

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which works just fine and when compiled you see the tabs and the button on the first pane.

but then when i try and ad an actionlistener to the button using the following code

Code:

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  addButton.addActionListener(this);

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i get this error:

Code:

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addActionListener(java.awt.event.ActionListener) in javax.swing.AbstractButton cannot be applied to (tester)
tester is the name of my class.

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Thanks

tester must implement ActionListener and have its only method implemented:

Code:

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class tester implements ActionListener {
    ...
    public void actionPerformed(ActionEvent e) {

    }
    ...
}

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in order to be a proper ActionListener for addButton.