The "return" keyword always has to do with exiting the current method (with a few peculiarities regarding the finally{} block). "break" will exit a switch statement.
In this case, "return" returns the flow to the "caller of main" which in this case, would be the JVM, I imagine.
You can
test this similarly by creating another function, with a return type of "void" - with this same switch statement. If you call this new function from main(), you'll note that the return statement "returns" the flow to main - and your //line 1 is never printed.