Help required converting a few lines of Python to Java (Android)

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Hi, I've been trying to implement the following Python example from the OpenCV docs into Java for OpenCV4Android:

http://docs.opencv.org/3.0-beta/doc/p...

I'm stuck on this particular part for the FLANN based matcher and was wondering if anyone could help me out:

FLANN_INDEX_KDTREE = 0
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks = 50)

flann = cv2.FlannBasedMatcher(index_params, search_params)

matches = flann.knnMatch(des1,des2,k=2)

// store all the good matches as per Lowe's ratio test. 
good = []
for m,n in matches:
    if m.distance < 0.7*n.distance:
        good.append(m)

So far I have:

DescriptorMatcher FLANN = DescriptorMatcher.create(1);
FLANN.knnMatch(descriptorsRef, descriptors, matches, 2);

I'm struggling to figure out how to express the index_params and search_params as well as the for loop for storing all the good matches as per Lowe's ratio test.

Any help would be very much appreciated!