Double probability = 0.0;
probability += Math.log((classCounts.get(currentClass)+ alpha)/(numOfTrainingExamples + alpha * classes.size())); //prior
subMap = classFeatureCounts.get(currentClass);
for(String token : docTokens){
    int classTokenCount = subMap.containsKey(token)?subMap.get(token):0;
    int classAllTokensCount = subMap.get("*");
    probability += Math.log((classTokenCount + alpha)/(classAllTokensCount + alpha * vocabularySize));
}