How to compute retail price with Java Swing?

import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class RetailPrice{

	public static void main(String[]args){
		SwingUtilities.invokeLater(createGUI());
	}

	private static Runnable createGUI(){
		return new Runnable(){
			@Override
			public void run(){
				JFrame f = new JFrame("Retail Price Calculator");
				Container pane = f.getContentPane();
				pane.setLayout(new FlowLayout());
				JTextField wholesaleTF = new JTextField(10);
				pane.add(new JLabel("Wholesale $"));
				pane.add(wholesaleTF);
				JTextField markupTF = new JTextField(2);
				pane.add(new JLabel("Markup %"));
				pane.add(markupTF);
				JTextField retailTF = new JTextField(10);
				pane.add(new JLabel("Retail $"));
				pane.add(retailTF);
				retailTF.setEditable(false);
				JButton btn = new JButton("Go");
				pane.add(btn);
				f.pack();
				f.setVisible(true);
				f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
				btn.addActionListener(clickHandler(wholesaleTF, markupTF, retailTF));
			}
		};
	}

	private static ActionListener clickHandler(JTextField wholesaleTF, JTextField markupTF, JTextField retailTF){
		return new ActionListener(){
			@Override
			public void actionPerformed(ActionEvent e){
				retailTF.setText("");
				try{
					double wholesale = new Double(wholesaleTF.getText());
					double markup = new Double(markupTF.getText());
					double retail = ((wholesale*(markup/100.0))+wholesale);
					retailTF.setText(String.format("%.2f",retail));
				}catch(NumberFormatException ex){
					retailTF.setText(ex.getMessage());
				}
			}
		};
	}
}

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