Java函数式接口Consumer

void accept(T t);

default Consumer<T> andThen(Consumer<? super T> after) {
        Objects.requireNonNull(after);
        return (T t) -> { accept(t); after.accept(t); };
    }

package jdk8.consumer;

import java.util.function.Consumer;

public class ConsumerTest {
    public static void main(String[] args) {

        ConsumerTest consumerTest = new ConsumerTest();
        consumerTest.arithmetic(8, 9, System.out::println, System.out::println);

        Consumer<String> consumer = s -> System.out.println(s.toUpperCase());
        consumer.accept("hello");

        consumerTest.arithmetic1(4, 9, System.out::println, (a) -> a = a + 2);
        consumerTest.arithmetic1(4, 9, System.out::println, (a) -> System.out.println(a * 2));
//        consumerTest.arithmetic1(4, 9, System.out::println, (a) -> a * 2);
        

    }

    public void arithmetic(int i, int s, Consumer<Integer> consumer, Consumer<Integer> consumer1) {
        consumer1.accept(i * s);
        consumer.accept(i + s);
    }

    public void arithmetic1(int a, int b, Consumer<Integer> consumer, Consumer<Integer> consumer1) {
        consumer.andThen(consumer1).accept(a + b);
    }
}

72
17
HELLO
13
13
26