Interesting difference between books and tutorials

Question

I started coding in Java about four years ago. When I started I learned from a book (that I no longer have), I think it was "Sam's Teach Yourself Java in 24 Hours". I was just a kid then and I became fairly proficient in all of the basic requirements and such. Now, four years later, I am looking into getting back to Java when I can find the time, and possibly getting a certification. Instead of the book, I now use the online tutorials and API docs. Something I noticed about the tutorials is that they use coding methods that I never saw in the book. For instance from this tutorial on using the SpringLayout, the code follows this syntax:
import /*neccessary items*/
public class SpringDemo1 {
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the                  <----I didn't add this. Guessing it has something
     * event-dispatching thread.                                    to do with preventing the thread from crashing...?
    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("SpringDemo1");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //SpringLayout code here....
        frame.pack();
        frame.setVisible(true);
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
}whereas, when I learned from the book, I always did this and I still do:
import /*neccessary items*/
public class myClass extends JFrame {
    public myClass() {
        //set up GUI here
    public static void main(String args[]) {
        myClass mc = new myClass();
}If I am going to get my certification, I don't want to be using practices that could cause a program to crash and get someone angry at me. If I am doing something wrong, please chew me out. It's better than losing a job...

Answer 1

The book is old-fashioned, that's all. Neither version of the code is so bad that it will crash and you will lose your job and become a drug addict accosting people on the street for money.
The "extends JFrame" version was the usual way to write things back in the early days of Java. And then people started thinking more about object orientation, and noticed that there was nothing in most Swing programs which created a modified JFrame. They simply used the features of a JFrame to get their work done.
So under the flag of "Prefer composition to inheritance", the OO people rewrote the standard Swing application to do that. And so they should... Java is an object-oriented language, after all, so why not do things right? Let's not extend JFrame (inheritance) if we can just create one and use it (composition).
Of course they couldn't go back and change all the paper books and all the thousands of programs that people had already written in the old way, but they could change the tutorials. And they did.
So my suggestion would be to follow the style shown in that tutorial. You won't lose your job over it. In fact being able to explain why you did it might even improve your status at your job.