Can someone help me and give an android example that use opencv machine learning with java code

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I am a beginner in opencv and android and i have a project that aims to detect text in a picture and then recognize this text (i should store letters(forms of pictures) in an sqlite database and then compare the letters found in the picture with those in the database and the app know each letters by reference to database .I can't use ocr system because the letters in the picture aren't clear (I tried ocr and the result was bad ,the app give me false result) so i search and i find that i can use opencv machine learning but i don't know how i do this .Please help me