一文带你掌握Java8中Lambda表达式 函数式接口及方法构造器数组的引用

目录

• 函数式接口概述
• 函数式接口示例
  • 1、Runnable接口
  • 2、自定义函数式接口
  • 3、作为参数传递 Lambda 表达式
• 内置函数式接口
• Lambda简述
• Lambda语法
• 方法引用
• 构造器引用
• 数组引用

@FunctionalInterface
public interface MyFunctional01{
    public String getValue();
}

//使用泛型
@FunctionalInterface
public interface MyFunctional02<T>{
    public T getValue(T t);
}

public class LambdaTest {
    public static void main(String[] args) {
        String newStr = toUpperString(str -> str.toUpperCase(),"abcDEf");
        System.out.println(newStr);
    }
    public static String toUpperString(MyFunc<String> my,String str){
        return my.getValue(str);
    }
}

@FunctionalInterface
interface MyFunc<T>{
    public T getValue(T t);
}

import java.util.function.Consumer;

/**
 * @Author: Yeman
 * @Date: 2021-10-03-22:50
 * @Description:
 */
public class LambdaTest {
    public static void main(String[] args) {
        Consumer<Integer> consumer = i -> System.out.println(i);
        consumer.accept(9);
    }
}

public class LambdaTest {
    public static void main(String[] args) {
        //未使用Lambda表达式
        Runnable runnable1 = new Runnable() {
            @Override
            public void run() {
                System.out.println("这是第一个语法！");
            }
        };
        runnable1.run();
        System.out.println("======================");
        //使用Lambda表达式
        Runnable runnable2 = () -> {
            System.out.println("这是用了Lambda表达式的一个语法！");
        };
        runnable2.run();
    }
}

import java.util.Comparator;
import java.util.function.Consumer;

/**
 * @Author: Yeman
 * @Date: 2021-10-03-22:50
 * @Description:
 */
public class LambdaTest {
    public static void main(String[] args) {

        Consumer<Integer> consumer = i -> System.out.println(i);
        consumer.accept(9);

        Consumer<String> stringConsumer = System.out :: println;
        stringConsumer.accept("Hello");

        Comparator<Integer> comparable = (x, y) -> Integer.compare(x,y);
        System.out.println(comparable.compare(2,9));

        Comparator<Integer> integerComparator = Integer :: compare;
        System.out.println(integerComparator.compare(9,2));
    }
}

import java.util.function.Function;

/**
 * @Author: Yeman
 * @Date: 2021-10-03-22:50
 * @Description:
 */
public class LambdaTest {
    public static void main(String[] args) {
        Function<Integer,String[]> function = length -> new String[length];
        String[] apply = function.apply(3);
        System.out.println(apply[2]);

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

        Function<Integer,String[]> function1 = String[] :: new;
        System.out.println(function1.apply(5));
    }
}