What does this line of code mean ?

[WeiJie Lim]

I see this similar line of code often in a Java book that I am reading.

String host = args.length > 0 ? args[0] : "localhost";

Why does it have to set it to args[0] if the argument length is >0 ?

Thanks.

[E Armitage]

The ternary operator is a short hand for if-else based assignment. If the array or arguments args has values then the first argument is assigned as the host, otherwise "localhost" is used as the as host. So if you call the program and provide an argument for the host then that argument value is used, if you call without any arguments then "localhost" is used.

[Saif Asif]

Why does it have to set it to args[0] if the argument length is >0

We can only tell that once we take a look at the program written in the book. As far as I can tell, this particular check is just making sure that the 'host' variable name is never null. The program that follows may be dependant on the presence of this variable name and therefore the author has added a check on this variable so that if user hasn't passed in any argument then set the 'host' to 'localhost'.

[WeiJie Lim]

E Armitage wrote:The ternary operator is a short hand for if-else based assignment. If the array or arguments args has values then the first argument is assigned as the host, otherwise "localhost" is used as the as host. So if you call the program and provide an argument for the host then that argument value is used, if you call without any arguments then "localhost" is used.

Thanks for the explanation