java的几个函数式接口案例

基本都是使用lambda表达式重写方法

Supplier

import java.util.function.Supplier;

//生产数据的接口
public class SupplierDemo {
    public static void main(String[] args) {
        //lambda表达式重写接口中方法
        String s = getString(() -> "chris");
        System.out.println(s);
        int i = getNumber(() -> 666);
        System.out.println(i);
    }
    
    //生产数据
    private static String getString(Supplier<String> supplier){
        return supplier.get();
    }

    private static int getNumber(Supplier<Integer> supplier){
        return supplier.get();
    }
}

Consumer

import java.util.function.Consumer;

public class ConsumerDemo {
    public static void main(String[] args) {
//        ConsumeString("chris", System.out::println);
//
//        ConsumeString("Tom",System.out::println,s -> System.out.println(new StringBuilder(s).reverse().toString()));

        String[] array = {"林青霞,30","张曼玉,33"};
        for (String s : array) {
            ConsumeString(s,s1 -> System.out.println(s.split(",")[0]),s1 -> System.out.println(s.split(",")[1]));
        }
    }
    
    //消费数据
    private static void ConsumeString(String s, Consumer<String> consumer){
        consumer.accept(s);
    }

    private static void ConsumeString(String s, Consumer<String> consumer,Consumer<String> stringConsumer){
        consumer.andThen(stringConsumer).accept(s);
    }

}

Predicate

import java.util.function.Predicate;

//逻辑判断
public class PredicateDemo {
    public static void main(String[] args) {
        String[] array = {"林青霞,30","柳岩,34","张曼玉,35","貂蝉,31"};
        for (String s : array) {
            if (PredicatePeople(s,s1 -> s1.split(",")[0].length() > 2,s1 -> Integer.parseInt(s1.split(",")[1]) > 33)){
                System.out.println(s);
            }
        }
    }

    private static boolean PredicatePeople(String s, Predicate<String> predicate, Predicate<String> stringPredicate){
        return predicate.and(stringPredicate).test(s);
    }
}

Function

import java.util.function.Function;
//数据转型
public class FunctionDemo {
    public static void main(String[] args) {
        String s = "林青霞,30";
        TestFunction(s,s1 -> Integer.parseInt(s1.split(",")[1])+70);
    }

    private static void TestFunction(String s, Function<String,Integer> function){
        int i = function.apply(s);
        System.out.println(i);
    }
}