函数式（Functional）接口

/*
java内置的4大核心函数接口

消费型接口 Consumer void accept(T t)
供给型接口 Supplier T get()
函数型接口 Function R apply(T t)
断定型接口 Predicate boolean test(T t)

package com.atguigu.java2;
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 Dxkstart
 * @create 2021-06-08 21:40
 */
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，去天上人间买了瓶矿泉水，价格为：" + aDouble);
            }
        });
        System.out.println("***********************");
        happyTime(400,money -> System.out.println("学习太累了，去天上人间喝了口水，价格为：" + 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;
    }
}