Java tutorial
//package com.java2s; /* * Copyright 2014 - 2016 Real Logic Ltd. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.util.List; import java.util.function.ToIntFunction; public class Main { /** * Garbage free sum function. * * @param values the list of input values * @param function function that map each value to an int * @param <V> the value to add up * @return the sum of all the int values returned for each member of the list. */ public static <V> int sum(final List<V> values, final ToIntFunction<V> function) { int total = 0; final int size = values.size(); for (int i = 0; i < size; i++) { final V value = values.get(i); total += function.applyAsInt(value); } return total; } }