Question

The RFC for a Java class is set of all methods that can be invoked in response to a message to an object of the class or by some method in the class. RFC = M + R where M = Number of methods in the class. R = Total number of other methods directly invoked from the M.

Thinking C is the .class and J is the .java file of which we need to calculate RFC.

 class J{   a(){}  b(){}  c(){    e1.e();    e1.f();    e1.g();  }  h(){    i.k();    i.j();   }   m(){}   n(){    i.o();    i.p();    i.p();    i.p();   } } 

here M=6 and R=9 (Don’t worry about call inside a loop. It’s considered as a single call)

Calculating M is easy. Load C using classloader and use reflection to get the count of methods.

Calculating R is not direct. We need to count the number of method calls from the class. First level only.

For calculating R I must use regex. Usually format would be (calls without using . are not counted)

 [variable_name].[method_name]([zero or more parameters]); 

or

 [variable_name].[method_name]([zero or more parameters]) 

with out semicolon when call return is directly becomes parameter to another method. or

 [variable_name].[method_name]([zero or more parameters]).method2(); 

this becomes two method calls

What other patterns of the method call can you think of? Is there any other way other than using RegEx that can be used to calculate R.

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UPDATE:
@McDowell Looks like using BCEL I can simplify the whole process. Let me try it.

Answer 1

You could use the Byte Code Engineering Library with binaries. You can use a DescendingVisitor to visit a class’ members and references. I’ve used it to find class dependencies.

Alternatively, you could reuse some model of the source files. I’m pretty sure the Java editor in the Eclipse JDT is backed by some form of model.