GroupBy functionalities

java8_groupbyValue.java

	private String getPredictedModule(List<Result> result) {
		Collector<Result, ?, Map<String, Double>> summarizeByModules = 
				Collectors.groupingBy(Result::getModule, Collectors.summingDouble(Result::getConfidence));
		Map<String, Double> finalMap = new LinkedHashMap<>();
		
	        result.stream().collect(summarizeByModules)
			.entrySet().stream().sorted(Map.Entry.<String, Double>comparingByValue()
                        .reversed()).forEachOrdered(e -> finalMap.put(e.getKey(), e.getValue()));
		return finalMap.keySet().stream().findFirst().get();
	}


/**
Explanation :
1.Grouping a list by its keyString.
2.While grouping adding all the valueString based on key.
3.Sort by value in descending order.
4.Return the first key from map.

Collectors.groupingBy( groupBy param, Condition to groupby)
Collectors.summingDouble() -> will yield sum [Collectors.summarizingDouble() -> will yield stats, even more powerful fn]
*/