Groovy (File IO): find all files and return all files - the Groovy way

Question

Ok, this should be easy...

I'm new to groovy and I'm looking to implement the following logic:

def testFiles = findAllTestFiles();

So far, I've come up with the code below which successfully prints all files names. However, instead of printing, I just need to put them into a collection. Of course, I could do this the old java way: just instantiate a collection, add all the elements and return it. However, that wouldn't teach me anything.

So how do you do this the cool, "Groovy" way?

static File[] findAllTestFiles() {
    def directory = new File("src/test/java");
    def closure = {File f -> if(f.name =~ /Test\.java$/) println f }
    directory.eachFileRecurse FileType.FILES, closure
    return null;
}

I'm looking to implement findAlltestFiles() in Groovy using as little code as possible while still being readable.

Answer 1

I'd try to avoid building the collection entirely. Using closures, you can separate the logic to select the files from what you actually want to do with them, like so:

import groovy.io.FileType

def withEachTestFile(Closure closure) {
    new File("src/test/java").eachFileRecurse(FileType.FILES) {
        if (it.name =~ /Test\.java$/) {
            closure.call(it)
        }
    }
}

Then if you want to do something on the test files, you can do it directly without building up a list in memory:

withEachTestFile() { println it }

or if you really want the list, you can easily generate it, using whatever collection makes sense:

def files = []
withEachTestFile() { files << it }

Answer 2

A newer, standard and more generic way to traverse a directory which supports multiple closure callbacks is traverse.

import static groovy.io.FileType.FILES
...
def files = [] 
new File("src/test/java").traverse(type: FILES, nameFilter: ~/Test\.java$/) {
    files << it    
}