Spring and the java.lang.NoSuchFieldError: NULL Exception

A few days ago I was going through a project's Maven dependencies, removing unused junk, checking jar file version numbers adding a little dependency management and generally tidying up (yes, I know that this isn't something we often get time to do, but even Maven dependencies can be a form of technical debt). After recompiling and running the unit tests I ran some end to end tests only to find that the whole thing fell apart... Big time.

The exception I got was the usual one that all Spring developers get, a

Spring MVC, Ajax and JSON Part 3 - The Client Side Code

If you’ve been following this short series of blogs on Spring, Ajax and JSON you’ll recall that I’ve got as far as creating a Spring MVC web application that displays a form, which allows the user to select a bunch of items and submit a request to the server to purchase them. The server then replies with some JSON allowing the user to confirm their purchases. If you already know all this you can now jump to HERE. If you’re wondering what I’m talking about then take a look at the first two blogs in this series:

• Spring MVC, Ajax and JSON Part 1 - Setting The Scene
• Spring MVC, Ajax and JSON Part 2 - The Server Side Code

HERE

Having completed the server side code then the next thing to do is to move on to the client side code,

Spring MVC, Ajax and JSON Part 2 - The Server Side Code

In my last blog I said that I was going to talk about Spring, Ajax and JSON, but didn't. The reason for this is that I wanted to set the scene using a (barely) credible shopping web site scenario. In this scenario when the user clicks on the eCommerce page link, the server app loads some the items from a catalogue and displays them on the page. The user then checks a number of items and presses 'Confirm Purchase'. Now, this is where Ajax and JSON come in, on pressing 'Confirm Purchase' the browser makes an Ajax request to the server sending it the item ids. The server then retrieves the items from the database returns them as JSON to the browser. The browser then processes the JSON, displaying the items on he screen.

My last blog got as far as creating and displaying a form that presented a list of items from the imaginary catalogue to the user. This blog takes a look at the next step in the project: creating some JSON.