Linux: command to open URL in default browser

Question

What command we have to execute (from Java, but that should not matter) on Linux (different common distributions) to open a given URL in the default browser?

Answer 1

###1     Desktop's -or- Console use:
sensible-browser $URL; # Opinion: best. Target preferred APP.
# My-Server translates to: w3m [options] [URL or filename] 
## [ -z "$BROWSER" ] && echo "Empty"
# Then, Set the BROWSER environment variable to your desired browser.

###2     Alternative 
# Desktop (if [command-not-found] out-Dated)
x-www-browser http://tv.jimmylandstudios.xyz # firefox

###3     !- A Must Know -!
# Desktop (/usr/share/applications/*.desktop)
xdg-open $URI # opens about anything on Linux (w/ .desktop file)