Personally, I’m not sure what any code editor thinks it is doing by not having line numbers switched on by default.
But, each to their own, so if you want to see your line numbers in Eclipse and you just can’t find out where on earth to turn them on, aaargh! Don’t panic.
Just go to:
Window -> Preferences -> General -> Editors -> Text Editors
And check the handy “Show line numbers” box:
Then, take a deep breath, and feel much better than you can now see which line of code you are editing at any given time.