Java内置的4大核心函数式接口_消费型 供给型 函数型 断定型

package com.zhou.java1;

import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Predicate;

/**
 * java 内置的 4 大核心函数式接口
 *
 * 消费型接口 Consumer<T>    void accept(T t)
 * 供给型接口 Supplier<T>    T get()
 * 函数型接口 Function<T,R>  R apply(T t)
 * 断定型接口 Predicate<T>   boolean test(T t)
 *
 * @author upzhou
 * @create 2022-04-03 17:42
 */
public class LambdaTest2 {

    @Test
    public void test1(){
        happyTime(500, new Consumer<Double>() {
            @Override
            public void accept(Double aDouble) {
                System.out.println("学习太累了,去消费了:" + aDouble);
            }
        });

        System.out.println("****************************");

        happyTime(400,money -> System.out.println("学习太无聊了,去消费了:" + money));

    }

    public void happyTime(double money, Consumer<Double> con){
        con.accept(money);
    }

    @Test
    public void test2(){

        List<String> list = Arrays.asList("北京", "南京", "天津", "东京", "西京", "普京");
        List<String> filterStrs = filterString(list, new Predicate<String>() {
            @Override
            public boolean test(String s) {
                return s.contains("京");
            }
        });
        System.out.println(filterStrs);

        List<String> filterStrs1 = filterString(list, s -> s.contains("京"));
        System.out.println(filterStrs1);

    }

    //根据给定的规则,过滤集合中的字符串. 此规则由 Predicate 的方法决定
    public List<String> filterString(List<String> list, Predicate<String> pre){

        ArrayList<String> filterList = new ArrayList<>();

        for (String s : list){
            if (pre.test(s)){
                filterList.add(s);
            }
        }
        return filterList;
    }

}