I was busy refactoring code in RestMud this morning because I want to try and open source the basic game engine, and then later the Web/REST API, but I want to tidy up the code a little first.

I've been working through the code:

• Moving classes into new packages
• Splitting classes to make code clearer and easier to manage
• New classes make code easier to test

And the more I tidy it up in general, the easier it is to spot smaller problems of code duplication.

Sometimes I fix the duplication by:

• Extracting code into a new class and delegating functionality off to the class
• Extracting code into private methods

IntelliJ has an incredibly useful piece functionality to help with that in the form of the Compare Tool.

The Compare Tool

The compare tool is a built-in diff tool.

I can use it in three different ways:

• Right-click on a file and "Compare" then choose a file on my hard drive to compare with
• Select two classes in the project view and right click to "Compare"
• Select code, add it into the clipboard, then highlight a different block of code and "Compare with Clipboard"

They all use the same 'diff' view, which is much easier than:

• Using a separate tool like WinMerge to compare files outside of the IDE.
• Splitting the window and visually trying to compare code

I show all three approaches in this short YouTube video.