lambda表达式的4种基础类型

import java.util.Date;;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.regex.Pattern;

/**
 * Predicate: 测试一个传入的参数是否符合要求
 * Consumer: 消费传入的参数，对传入的参数进行对应的处理
 * Function: 对传入的T类型参数转换成R类型的返回
 * Supplier: 生成一个T类型的对象，类似Factory方法
 */
public class Test {
    public static void main(String[] args) {
        Predicate isNumber = (s) -> {
            Pattern pattern = Pattern.compile("-?[0-9]+.?[0-9]+");
            return pattern.matcher(s.toString()).matches();
        };
        System.out.println(isNumber.test("23"));

        Consumer kafkaConsumer = (s) -> {
            System.out.println("kafka consume " + s);
        };
        Consumer rocketmqConsumer = (s) -> {
            System.out.println("rocketmq consume " + s);
        };
        kafkaConsumer.andThen(rocketmqConsumer).accept("hello");
        Function<Integer, Integer> function = (Integer s) -> s + 1;
        System.out.println(function.andThen(function).andThen(function).apply(0));

        Function<String, Integer> str2int = (s) -> Integer.parseInt(s);
        Function<Integer, Date> int2date = (i) -> new Date(i);
        System.out.println(str2int.andThen(int2date).apply("1234"));

        Supplier currenttimeSupplier = () -> System.currentTimeMillis();
        System.out.println(currenttimeSupplier.get());
    }
}