How to Search and count pattern from list of files in java

I have a list of files in a folder and need to search 3 patterns/words and count no. Of occurences of specific types. Example, in these 3 patterns I will a colors (Red, Blue, Green etc..) and each of these colors has START (First index) and END(last Index). I need to fetch the count each of these indexes for each colors. Hope my question is clear, please let me know How can i achieve it