# Measurement Details

The original definition of the metrics, and implementation details of both the program, and the Java language provide some leeway on how the metrics are measured. The following list contains the most important decisions. These are marked in the source code with a comment, such as the following.

    /* Measuring decision: couple interfaces */

- Interfaces are measured when considering a class's coupling. Rationale: changes to the interface may well require changes to the class.
- Use of Java SDK classes (java.*, javax.*, and some others) does not count toward a class's coupling. Rationale: the Java SDK classes are relatively stable, in comparison to the rest of the project. A command line argument switch (`-s`) is available for including the Java SDK classes into the calculation.
- Calls to JDK methods are included in the RFC calculation. Rationale: the method calls increase the class's complexity.
- The classes used for catching exceptions contribute toward the class's coupling measurements. Rationale: at the point where an exception is caught a new object of the corresponding type is instantiated.
- The complexity of each method is considered 1, when calculating WMC. Rationale: ease of implementation, and compatibility with Chidamber and Kemerer.
- LCOM is calculated following the 1994 paper description, and not by looking at disjoint graph components. Rationale: ease of implementation, and compatibility with Chidamber and Kemerer.
- RFC is calculated up to the first method call level, and not through the transitive closure of all method calls. Rationale: ease of implementation, and compatibility with Chidamber and Kemerer.
- A class's own methods contribute to its RFC. Rationale: the original Chidamber and Kemerer article describes RFC as a union of the set of methods called by the class and the set of methods in the class.

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