JAVA8方法推导 Lambda方法推导详细解析什么情况下可以进行方法推导?类的方法（静态方法）对象的方法构造方法自定义函数式接口范例：package com.example.study.java8.InterfaceFunction; import java.util.Arrays; import java.util.Comparator; import java.util.List; import java.util.function.BiFunction; import java.util.function.Consumer; import java.util.function.Function; import java.util.function.Supplier; /** * 方法推导 * 什么情况下可以进行方法推导： * 1、类的方法（静态方法） * 2、对象的方法 * 3、构造方法 */ public class MethodReferenceUsageDemoOne { public static void main(String[] args) { //方法推导，范例一：类的方法 //原始写法 Consumer<String> consumer = s-> System.out.println(s); genericityConsumer(consumer, "hello"); //1、进化一 genericityConsumer(s->System.out.println(s), "world"); //2、进化二 genericityConsumer(System.out::println, "nice"); System.out.println("==========================="); //方法推导，范例二：类的方法 List<Apple> list = Arrays.asList(new Apple("red", 10) , new Apple("red", 60) , new Apple("blue", 40) , new Apple("black", 30) , new Apple("green", 80) , new Apple("blue", 90) , new Apple("green", 60) , new Apple("green", 50) , new Apple("red", 20)); System.out.println(list); list.sort((oneParameter,twoParameter)->oneParameter.getColor().compareTo(twoParameter.getColor())); System.out.println(list); System.out.println("============排序另一种写法==============="); //排序另一种写法 List<Apple> list2= Arrays.asList(new Apple("red", 10) , new Apple("red", 60) , new Apple("blue", 40) , new Apple("black", 30) , new Apple("green", 80) , new Apple("blue", 90) , new Apple("green", 60) , new Apple("green", 50) , new Apple("red", 20)); System.out.println(list2); list2.sort(Comparator.comparing(Apple::getColor)); //排序说明： //1、匿名内部类 //2、上面第一种写法 //3、上面第二种写法 //代码越来越简单 System.out.println("==========================="); //方法推导，范例三：类的方法 //原始写法 list.stream().forEach(apple->System.out.println(apple)); System.out.println("==========================="); //进化1 list.stream().forEach(System.out::println); System.out.println("==========================="); //方法推导，范例四：类的方法 //原始写法 Integer integer = Integer.parseInt("123"); System.out.println(integer); System.out.println("==========================="); //进化 Function<String, Integer> function = Integer::parseInt; Integer integerTwo = function.apply("321"); System.out.println(integerTwo); System.out.println("==========================="); //方法推导，范例五：对象的方法 BiFunction<String, Integer, Character> stringIntegerCharacterBiFunction = String::charAt; Character character = stringIntegerCharacterBiFunction.apply("Hello", 1); System.out.println(character); System.out.println("==========================="); //方法推导，范例六：构造方法,1个参数 Supplier<String> supplier = String::new; String str = supplier.get(); System.out.println(str.getClass()); System.out.println("==========================="); //方法推导，范例七：构造方法,2个参数 //说明：Apple::new; 就是掉构造方法，自动推导参数和类型 BiFunction<String,Integer,Apple> appleBiFunction = Apple::new; Apple apple = appleBiFunction.apply("red", 50); System.out.println(apple); System.out.println("==========================="); //方法推导，范例八：构造方法-自定义FunctionalInterface接口,多个参数 CustomThreeFunctionalInterface<String,Integer,String,ComplexApple> appleSupplier = ComplexApple::new; ComplexApple complexApple = appleSupplier.apply("苹果",20,"green"); System.out.println(complexApple); } /** * 泛型Consumer * @param consumer * @param t * @param <T> */ public static <T> void genericityConsumer(Consumer<T> consumer, T t){ consumer.accept(t); } } 自定义函数式接口package com.example.study.java8.InterfaceFunction; /** * 自定义多个参数函数接口，创建对象 */ @FunctionalInterface public interface CustomThreeFunctionalInterface<T, U, K, R> { R apply(T t, U u, K k); } ComplexApplepackage com.example.study.java8.InterfaceFunction; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; import lombok.ToString; /** * 多个参数，构造方法推导 */ @Data @AllArgsConstructor @NoArgsConstructor @ToString public class ComplexApple { private String color; private Integer weight; private String name; } 主要讲解了，Lambda方法推导的常见用法。