File name vs. class name?

Question

I'm confused.
I'm working through some tutorials and lessons teaching myself Java.
I have yet to read anything regarding the name of the file vs. any names within the program.
The name of the file has to match what exactly?
The name of.....

Answer 1

A file can only have one public class andthat
class must be the same as the file name. The same
file can, however, have any number of package level
classes with any name:I would suggest not using this feature except for junk
code.Really? I've use this all the time, I think for convenience, but maybe I'm doing something that I shouldn't be doing. In most cases, I will keep my JTable models in the same Class file where I use the JTable, and for example on an editor I wrote in Swing, I also keep all the Action blocks within the Editor class (they look like this, but there are probably 20 of them):
class TActionSetBackground extends AbstractAction {
    private final Frame parent;
    public TActionSetBackground(Frame frame) {
        super("Set background");
        parent = frame;
        super.putValue(AbstractAction.SHORT_DESCRIPTION, "Set Background");
        super.putValue(AbstractAction.SMALL_ICON, getImageIcon(iiI, "BackgroundColor", 24));
        super.putValue(AbstractAction.MNEMONIC_KEY,new Integer(KeyEvent.VK_B));
        //super.putValue(Action.ACCELERATOR_KEY,KeyStroke.getKeyStroke(KeyEvent.VK_W,Event.CTRL_MASK));
    public void actionPerformed(ActionEvent e) {
        actionSetBackground();
class TActionSetForeground extends AbstractAction {
    private final Frame parent;
    public TActionSetForeground(Frame frame) {
        super("Set Foreground");
        parent = frame;
        super.putValue(AbstractAction.SHORT_DESCRIPTION, "Set Foreground");
        super.putValue(AbstractAction.SMALL_ICON, getImageIcon(iiI, "ForegroundColor", 24));
        super.putValue(AbstractAction.MNEMONIC_KEY,new Integer(KeyEvent.VK_B));
        //super.putValue(Action.ACCELERATOR_KEY,KeyStroke.getKeyStroke(KeyEvent.VK_W,Event.CTRL_MASK));
    public void actionPerformed(ActionEvent e) {
        actionSetForeground();
}I am curious why this would be considered bad form. The additional maintenance of moving all these action blocks into their own files, and subsequent changes to allow access to the blocks seems like extra work to me without much benefit. I wouldn't change what I have already coded, but if there are good reasons (and ways) to do this differently, I would like to learn.