There are many ways to measure a code base. The most common way is to count the number of lines of code. This metric gives a rough estimation of the effort that had been put in to develop the code base. It also allows you to obtain a quality level agreement by pinpointing fat methods and classes.
JArchitect counts the number of lines of code. It also comes with more than 80 other code metrics. Some of them are related to your code organization (the number of classes or Packages, the number of methods declared in a class...), some of them are related to code quality (complexity, percentage of comments, number of parameters, cohesion of classes, stability of Projects...), some of them are related to the structure of code (which types are the most used, depth of inheritance...).