CSC 101 - URL

In this assignment, you will write a processing program named url.pde that extracts the various components of a URL. Your program will allow the user to type in a web URL. Once they have types on in, they can hi the enter key (\n) to see the components extracted. Below is an example of the program working with a sample URL:

Notice a few things:

• When the program is first run, the labels for URL, Protocol, Domain, etc are all present on the canvas.
• The color of the URL: text and the URL sub-components is different. You don’t need to choose the same colors, but you should choose different ones that are easily readable against the background.
• When the user types, the URL shows up next to the URL: label.
• When the user hits enter, the components of the URL are extracted and displayed, and the full URL is cleared.
• After hitting enter, and user can type another URL for the program to process.

Your program should use Strings and various string methods to “extract” the parts of the URL. In particular, you’ll want to use String.indexOf(), String.substring(), and string concatenation. Review the class slides if you don’t understand these well!

In terms of extracting the components, recall:

• The protocol is everything before and including the :// in the URL.
• The domain is everything between where the protocol ends and where the top-top-level domain (.com, .net, etc) begins.
• The top level domain is the .com/.net/.org/etc part of the URL. For the purposes of this assignment, you can assume that the top-level domain will always be either .com, .net or .org.
• The path is all of the text after the top-level domain.

Error Handling

When a valid URL is typed in, your program should be able to extract all of the components. However, what if a user types in garbage?

Your program must handle this, to a small degree. Before you try to extract the components, you program should check:

• Does the URL not contain ://?
• Does the URL contain neither .com nor .net, .org?

If either of these are true, it should display INVALID URL in red instead of the extracted components. For example:

These are some examples of good URLs:

• http://google.com/docs/index.html
• http://www.web.net/a/b/c/x
• http://benjdd.com/index.html
• http://www.arizona.org

Some invalid URLS (which your program should be able to determine are bad) are:

• arizona.org/index.html
• http://google.io/hello
• these are some words!
• http://hello.something.other.index.html

Development Strategy

I recommend beginning by getting all of the labels up on the screen, with the correct colors. Don’t implement the code to let the user actually enter in text yet.

Then, modify the code so that the user can enter in some text, and hit enter to clear it:

Now, add code to check if the URL is invalid, using the rules described earlier.

Lastly, modify the code so that it correctly extracts all of the URL components.

Submission

This program is due on Friday, March 30th at 5:00pm. Turn in the one processing code file to the D2L dropbox.