Regex that Will Match a Java Method Declaration

Question

I need a Regex that will match a java method declaration. I have come up with one that will match a method declaration, but it requires the opening bracket of the method to

Answer 1

A tip:

If you are going to write the regex in Perl, please use the "xms" options so that you can leave spaces and document the regex. For example you can write a regex like:

 m{\w+ \s+      #return type
   \w+ \s*      #function name
   [(] [^)]* [)] #params
   \s* [{]           #open paren
  }xms

One of the options (think x) allows the # comments inside a regex. Also use \s instead of a " ". \s stands for any "blank" character. So tabs would also match -- which is what you would want. In Perl you don't need to use / /, you can use { } or < > or | |.

Not sure if other languages have this ability. If they do, then please use them.

Answer 2

I built a vim regex to do this for ctrlp/funky based on Georgios Gousios's answer.

    let regex = '\v^\s+'                " preamble
    let regex .= '%(<\w+>\s+){0,3}'     " visibility, static, final
    let regex .= '%(\w|[<>[\]])+\s+'    " return type
    let regex .= '\w+\s*'               " method name
    let regex .= '\([^\)]*\)'           " method parameters
    let regex .= '%(\w|\s|\{)+$'        " postamble

I'd guess that looks like this in Java:

^\s+(?:<\w+>\s+){0,3}(?:[\w\<\>\[\]])+\s+\w+\s*\([^\)]*\)(?:\w|\s|\{)+$

Answer 3

(public|private|static|protected|abstract|native|synchronized) +([a-zA-Z0-9<>._?, ]+) +([a-zA-Z0-9_]+) *\\([a-zA-Z0-9<>\\[\\]._?, \n]*\\) *([a-zA-Z0-9_ ,\n]*) *\\{

The Regex above will detect all possible java method definitions. Tested on lot's of source code files. To include constructors as well use the below regex :

(public|private|static|protected|abstract|native|synchronized) +([a-zA-Z0-9<>._?, ]*) +([a-zA-Z0-9_]+) *\\([a-zA-Z0-9<>\\[\\]._?, \n]*\\) *([a-zA-Z0-9_ ,\n]*) *\\{

Answer 4

I found seba229's answer useful, it captures most of the scenarios, but not the following,

public <T> T name(final Class<T> x, final T y)

This regex will capture that also.

((public|private|protected|static|final|native|synchronized|abstract|transient)+\s)+[\$_\w\<\>\w\s\[\]]*\s+[\$_\w]+\([^\)]*\)?\s*

Hope this helps.

Answer 5

This is for a more specific use case but it's so much simpler I believe its worth sharing. I did this for finding 'public static void' methods i.e. Play controller actions, and I did it from the Windows/Cygwin command line, using grep; see: https://stackoverflow.com/a/7167115/34806

cat Foobar.java | grep -Pzo '(?s)public static void.*?\)\s+{'

The last two entries from my output are as follows:

public static void activeWorkEventStations (String type,
            String symbol,
            String section,
            String day,
            String priority,
            @As("yyyy-MM-dd") Date scheduleDepartureDate) {
public static void getActiveScheduleChangeLogs(String type,
            String symbol,
            String section,
            String day,
            String priority,
            @As("yyyy-MM-dd") Date scheduleDepartureDate) {

Answer 6

(public|private|static|protected) ([A-Za-z0-9<>.]+) ([A-Za-z0-9]+)\(

Also, here's a replace sequence you can use in IntelliJ

$1 $2 $3(

I use it like this:

$1 $2 aaa$3(

when converting Java files to Kotlin to prevent functions that start with "get" from automatically turning into variables. Doesn't work with "default" access level, but I don't use that much myself.