Java内置的4大核心函数式接口

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Java内置的4大核心函数式接口

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package com.atguigu.java1;

import org.junit.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 liangqichen
 * @create 2021-11-02 9:46
 */
public class LambdaTest2 {

    @Test
    public void test1() {
        happyTime(500, new Consumer<Double>() {
            @Override
            public void accept(Double aDouble) {
                System.out.println("学习太累啦，去购物，花费" + aDouble);
            }
        });

        System.out.println("*********************************");
        happyTime(400, money -> System.out.println("花了400，haha" + money));
    }


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

    @Test
    public void test2(){
        List<String> list = Arrays.asList("北京","天津","南京");
        List<String> filterString = filtetString(list, new Predicate<String>() {
            @Override
            public boolean test(String s) {
                return s.contains("京");
            }
        });
        System.out.println(filterString);

         /// List<String> filterString1 = filterString(list,s -> s.contains("京"));


    }

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

        ArrayList<String> filterList = new ArrayList<>();
        for (String s : list){
            if (pre.test(s)){
                filterList.add(s);
            }
        }
        return filterList;
    }
}