Other URL Constructors

The URL class provides two additional constructors for creating a URL object. These constructors are useful when you are working with URLs, such as HTTP URLs, that have host name, filename, port number, and reference components in the resource name portion of the URL. These two constructors are useful when you do not have a String containing the complete URL specification, but you do know various components of the URL.
For example, suppose you design a network browsing panel similar to a file browsing panel that allows users to choose the protocol, host name, port number, and filename. You can construct a URL from the panel's components. The first constructor creates a URL object from a protocol, host name, and filename. The following code snippet creates a URL to the Gamelan.net.html file at the Gamelan site:

new URL("http", "www.gamelan.com", "/pages/Gamelan.net.html");

This is equivalent to

new URL("http://www.gamelan.com/pages/Gamelan.net.html");

The first argument is the protocol, the second is the host name, and the last is the pathname of the file. Note that the filename contains a forward slash at the beginning. This indicates that the filename is specified from the root of the host. The final URL constructor adds the port number to the list of arguments used in the previous constructor:

URL gamelan = new URL("http", "www.gamelan.com", 80,
                       "pages/Gamelan.network.html");

This creates a URL object for the following URL:

http://www.gamelan.com:80/pages/Gamelan.network.html

If you construct a URL object using one of these constructors, you can get a String containing the complete URL address by using the URL object's toString method or the equivalent toExternalForm method.