Regular expression to identify java function

Question

I am trying to identify a java function block addition in a diff file (new line start with + in diff). For that I am using regular expression.

It is working fine, however I need to identify all (if not, at least maximum) possible combinations of keyword used in java method declarations.

Here is my regular expression written in my java program

Pattern functionPatter = Pattern.compile("\\+\\s*(public|private|protected)?(\\s+static)?(\\s+final)?\\s+\\w+\\s+\\w+\\s*\\(.*?\\)\\s*(throws .*)+\\{.*\\}",Pattern.DOTALL); 

Please suggest me if I am missing anything.

Answer 1

I have no idea what you are trying to match with \\s+\\w+\\s+\\w+\\s*. If you are looking for a return type, then that won't do at all.

It appears that you are trying to match the function body using \\{.*\\}. That won't work, because braces may be nested, and regular expressions cannot handle nesting.

Modifier keywords can appear in any order, and you are missing a few, such as:

• synchronized
• transient
• volatile
• strictfp

If you want to implement this correctly, don't just make assumptions based on code that you have been seeing. Read the Java Language Specification.

Answer 2

For the java spec there are already complete parsers based e.g. on JavaCC or Antlr. IMHO the safest way would be process a java file using one of those and extracting the methods from there. Processing using regular expressions is quite difficult, e.g. how about methods in comments.

https://github.com/antlr/grammars-v4/tree/master/java8

• Sharon Ben Asher: or methods as String value String m = "public static void main()";