premetto che sono un novellino, sto iniziando a sviluppare con interfaccia grafica solo da poco tempo, e sono decisamente convinto di voler capire il FlowLayout, con questa occasione vado nella documentazione ufficiale, e per acquisire più familiarità col codice decido di scaricare la demo. Quello che vi chiedo in questo momento, è quello di spiegarmi gentilmente alcune righe di cui non riesco a comprendere l'utilizzo, riporto qua sotto il codice per comodità:
codice:
package layout;

/*
*
* FlowLayoutDemo.java
*
*/

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

public class FlowLayoutDemo extends JFrame{
    JRadioButton RtoLbutton;
    JRadioButton LtoRbutton;
    FlowLayout experimentLayout = new FlowLayout();
    final String RtoL = "Right to left";
    final String LtoR = "Left to right";
    JButton applyButton = new JButton("Apply component orientation");
    
    public FlowLayoutDemo(String name) {
        super(name);   ///
    }
    
    public void addComponentsToPane(final Container pane) {
        final JPanel compsToExperiment = new JPanel();
        compsToExperiment.setLayout(experimentLayout);
        experimentLayout.setAlignment(FlowLayout.TRAILING);
        JPanel controls = new JPanel();
        controls.setLayout(new FlowLayout());
        
        LtoRbutton = new JRadioButton(LtoR);
        LtoRbutton.setActionCommand(LtoR);
        LtoRbutton.setSelected(true);
        RtoLbutton = new JRadioButton(RtoL);
        RtoLbutton.setActionCommand(RtoL);
        
        //Add buttons to the experiment layout
        compsToExperiment.add(new JButton("Button 1"));
        compsToExperiment.add(new JButton("Button 2"));
        compsToExperiment.add(new JButton("Button 3"));
        compsToExperiment.add(new JButton("Long-Named Button 4"));
        compsToExperiment.add(new JButton("5"));
        //Left to right component orientation is selected by default
        compsToExperiment.setComponentOrientation(
                ComponentOrientation.LEFT_TO_RIGHT);
        
        //Add controls to set up the component orientation in the experiment layout
        final ButtonGroup group = new ButtonGroup();
        group.add(LtoRbutton);
        group.add(RtoLbutton);
        controls.add(LtoRbutton);
        controls.add(RtoLbutton);
        controls.add(applyButton);
        
        //Process the Apply component orientation button press
        applyButton.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                String command = group.getSelection().getActionCommand();
                //Check the selection
                if (command.equals("Left to right")) {
                    compsToExperiment.setComponentOrientation(
                            ComponentOrientation.LEFT_TO_RIGHT);
                } else {
                    compsToExperiment.setComponentOrientation(
                            ComponentOrientation.RIGHT_TO_LEFT);
                }
                //update the experiment layout
                compsToExperiment.validate(); ///
                compsToExperiment.repaint(); ///
            }
        });
        pane.add(compsToExperiment, BorderLayout.CENTER);
        pane.add(controls, BorderLayout.SOUTH); ;
    }
    
    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event dispatch thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        FlowLayoutDemo frame = new FlowLayoutDemo("FlowLayoutDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Set up the content pane.
        frame.addComponentsToPane(frame.getContentPane());
        //Display the window.
        frame.pack();   ///
        frame.setVisible(true);
    }
    
    public static void main(String[] args) {
        /* Use an appropriate Look and Feel */
        try {
            //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
        } catch (UnsupportedLookAndFeelException ex) {
            ex.printStackTrace();
        } catch (IllegalAccessException ex) {
            ex.printStackTrace();
        } catch (InstantiationException ex) {
            ex.printStackTrace();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        }
        /* Turn off metal's use of bold fonts */
        UIManager.put("swing.boldMetal", Boolean.FALSE); ///
        //Schedule a job for the event dispatchi thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() { ///
            public void run() {
                createAndShowGUI();
            }
        });
    }
}
ho contrassegnato con 3 slash (///) tutto ciò che non ho capito. Vorrei anche capire come mai tratta come frame l'oggetto "FlowLayoutFrame" anzichè creare un oggetto JFrame.
Spero di non chiedere troppo. Grazie.