That syntax is the way Java (and JNI, but I doubt that's being used here) looks up a method using a string argument. In this case, it is trying to look up a method called "a", which is a member of class "wj", from FCBlockStokedFire.java. This "a" method is a void method, and takes the parameters (ry, int, int, int, int, Random, int). The method definition would likely look something like this:
public void a( ry myRy, int i1, int i2, int i3, int i4, Random rnd, int i5 ) {
...etc
Judging from the variable names, this was either written by someone inconsiderate of other developers, or it's been obfuscated (probably the latter). If you don't have a class called "wj" in your project, then it is probably a member of an external jar your program is supposed to link to. Make sure your project is set up correctly and linked with all the required external dependencies. Check path names and file permissions as well.
