Here you can find the source of sumDouble(Collection
public static Double sumDouble(Collection<Double> collection)
//package com.java2s; //License from project: Open Source License import java.util.Collection; public class Main { public static Double sumDouble(Collection<Double> collection) { Double result = 0.0;/*from www .ja va2 s . c o m*/ for (Double n : collection) { result += n; } return result; } }