Thread: Action Listener Error

I get this error:

LBMPG.java:51: LBMPG.CalcButtonListener is not abstract and does not override abstract method actionPerformed(java.awt.event.ActionEvent) in java.awt.event.ActionListener
private class CalcButtonListener implements ActionListener
^

This is my code:

import javax.swing.*;
import java.awt.event.*;
 
public class LBMPG extends JFrame
{
	private JPanel panel;
	private JLabel gallonLabel;
	private JLabel milesLabel;
	private JTextField gallonsTextField;
	private JTextField milesTextField;
	private JButton calcButton;
	private final int WINDOW_WIDTH = 400;
	private final int WINDOW_HEIGHT = 100;
 
 
 
public LBMPG()
{
	setTitle("Miles per Gallon");
	setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	buildPanel();
	add(panel);
	setVisible(true);
}
 
private void buildPanel()
{
	gallonLabel = new JLabel("Enter the amount of gallons your tank holds:");
	gallonsTextField = new JTextField(2);
	milesLabel = new JLabel("Enter the amount of miles you can go on a full tank:");
	milesTextField = new JTextField(3);
	calcButton = new JButton("Calculate MPG");
	calcButton.addActionListener(new CalcButtonListener());
 
	panel = new JPanel();
	panel.add(gallonLabel);
	panel.add(gallonsTextField);
	panel.add(milesLabel);
	panel.add(milesTextField);
	panel.add(calcButton);
}
 
private class CalcButtonListener implements ActionListener
{
public void actionPerfmored(ActionEvent e)
{
	String input;
	double mpg;
	double gallons;
	double miles;
 
	input = gallonsTextField.getText();
	gallons = Double.parseDouble(input);
	input = milesTextField.getText();
	miles = Double.parseDouble(input);
 
	mpg = miles / gallons;
 
	JOptionPane.showMessageDialog(null, "Your car gets approximately " + mpg + " miles per gallon.");
 
}
}
}

I don't understand it. I've looked up things to fix it, but they didn't work. It's also weird because I pretty much followed another code to get the basic outline, and then changed everything to fit this scenario.