Toolbar (Swing)

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

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JPanel;

public class Toolbar extends JPanel implements ActionListener{

    // Variables-components
    private JButton helloButton;
    private JButton goodbyeButton;
    private StringListener textListener;                        // ΟΡΙΖΩ ΝΕΑ ΜΕΤΑΒΛΗΤΗ ΤΥΠΟΥ TextPanel, την textPanelHere, στην οποία θα ανατεθεί η γενική μεταβλητή/component textPanel

    // Constructor
    public Toolbar() {

        setBorder(BorderFactory.createEtchedBorder());
        // Initialize the variables
        helloButton = new JButton("Hello");
        goodbyeButton = new JButton("Goodbye");

        // Listen to the buttons
        helloButton.addActionListener(this);                // Katalavainei otan patietai to koumpi
        goodbyeButton.addActionListener(this);

        // Create the layout and add the 2 buttons
        setLayout(new FlowLayout());
        add(helloButton);
        add(goodbyeButton);

    }

    // Methods
    public void setStringListener(StringListener listener) {
        this.textListener = listener;
    }

    // Unimplemented Method
    @Override
    public void actionPerformed(ActionEvent e) {
        JButton clicked = (JButton)e.getSource();       // Orizw ena JButton pou diavazei to source (typou JButton) tou event(patima koumpiou) e
                                                // diladi to clicked ginetai (san timi) h helloButton h goodbyeButton
        if(clicked == helloButton) {
            //System.out.println("Hello (console)");                        // Τι γίνεται σε κονσόλα και JFrame, όταν πατήσω το κουμπί
            if(textListener != null) {
                textListener.textEmitted("Hello\n");
            }
        }
        else {
            //System.out.println("Goodbye (console)");
            if(textListener != null) {
                textListener.textEmitted("Goodbye\n");
            }
        }

    }

}