package Java8;

import java.util.Arrays;

import java.util.List;

import java.util.function.Predicate;

public class Example3 {

public static void main(String[] args) {

List<Integer> values = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);

System.out.println("Using Java7");

System.out.println("All - " + sumOfAll(values));

System.out.println("Even - " + sumOfEven(values));

System.out.println("Odd - " + sumOfOdd(values));

System.out.println("Using Java8 - type 1");

System.out.println("All - " + sumOfValuesType1(values, e -> true));

System.out.println("Even - " + sumOfValuesType1(values, e -> e % 2 == 0));

System.out.println("Odd - " + sumOfValuesType1(values, e -> e % 2 != 0));

System.out.println("Using Java8 - type 2");

System.out.println("All - " + sumOfValuesType2(values, e -> true));

System.out.println("Even - " + sumOfValuesType2(values, e -> e % 2 == 0));

System.out.println("Odd - " + sumOfValuesType2(values, e -> e % 2 != 0));

}

// Instead of 3 will create only one method and use predicate

private static Integer sumOfValuesType1(List<Integer> values, Predicate<Integer> selector) {

int sum = 0;

for (Integer value : values) {

if (selector.test(value)) {

sum += value;

}

}

return sum;

}

private static Integer sumOfValuesType2(List<Integer> values, Predicate<Integer> selector) {

return values.stream().filter(selector).reduce(0, (c, e) -> c + e);

}

private static Integer sumOfAll(List<Integer> values) {

int sum = 0;

for (Integer value : values) {

sum += value;

}

return sum;

}

// Even %2 == 0

private static Integer sumOfEven(List<Integer> values) {

int sum = 0;

for (Integer value : values) {

if (value % 2 == 0)

sum += value;

}

return sum;

}

// odd %2 !=0

private static Integer sumOfOdd(List<Integer> values) {

int sum = 0;

for (Integer value : values) {

if (value % 2 != 0)

sum += value;

}

return sum;

}

}