Re: Newbie needs help understanding code snippet
NoSpam@aol.com wrote:
I went through the 1st part of Sun's tutorial then had to quit for about a
month. Now I'm starting again at the beginning of the part on swing. I
don't understans a statement in an example, probably because I forgot some
syntax I studied earlier but can't find now. Here is the code:
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
createAndShowGUI is defined in the example. I do not understand the
argement to invokeLater. Could someone explain each part of the argument?
What to the statements and {} within an agrument mean?
Thanks!!!
The snippet you probably need to understand is this:
new Runnable() {
public void run() {
createAndShowGUI();
}
}
Runnable is an interface. The snippet defines a brand new class that
implements the Runnable interface, and then creates a new instance of
that class. This is called an anonymous class, because it doesn't have
any name associated with it (well, behind the scenes it does, but you
don't worry about that generally)
So, you can do something like this:
public static void main(String[] args) {
Runnable runnable = new Runnable() {
public void run() {
System.out.println("This is run!");
}
}
// Now, runnable is a Runnable object with an implementation for run()
runnable.run();
System.out.println("This is main!");
// invoke again.
runnable.run();
}
So now, the SwingUtilities.invokeLater() call is taking a Runnable object.
BTW, SwingUtilities.invokeLater() should be replaced with
EventQueue.invokeLater() when possible. They do the same thing,
SwingUtilities is just older (and calls upon EventQueue itself)
--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>