函数型接口-断定型接口-消费型接口-供给型接口

一、函数型接口
import java.util.function.Function;

public class Demo01 {
    public static void main(String[] args) {
        Function function = new Function<String, String>() {
            @Override
            public String apply(String str) {
                return str;
            }
        };
        //lambda表达式
        //Function<Integer, Integer> function1 = (number)->{return number * number;};
        //更加简化，去掉number的括号
        Function<Integer, Integer> function1 = number->{return number * number;};
        System.out.println(function1.apply(4));
    }
}

二、断定型接口（返回值只能是bool值）

import java.util.function.Predicate;

public class Demo02 {
    public static void main(String[] args) {
        Predicate objectPredicate = new Predicate<String>(){
            @Override
            public boolean test(String s) {
                return false;
            }
        };
        //lambda表达式
        Predicate objectPredicate1 = str->{return false;};
        System.out.println(objectPredicate1.test("111"));
    }
}

三、消费型接口（只有输入参数，没有返回值）

import java.util.function.Consumer;

public class Demo03 {
    public static void main(String[] args) {
        Consumer stringConsumer = new Consumer<String> (){
            @Override
            public void accept(String s) {
                System.out.println(s);
            }
        };
        Consumer<String> consumer = str->{};
    }
}

四、供给型接口（没有输入参数，只有返回值）

import java.util.function.Supplier;

public class Demo04 {
    public static void main(String[] args) {
        Supplier objectSupplier = new Supplier<Integer>(){
            @Override
            public Integer get() {
                return 1024;
            }
        };
        //lamdba表达式
        Supplier<Integer> supplier = ()->{return 1024;};
        System.out.println(objectSupplier.get());
    }
}