1.接口中default方法
package com.jdk8new.defau;
public interface Car1 {
default void print(){
System.out.println("我是BMW");
}
}
package com.jdk8new.defau;
public interface Car2 {
default void print(){
System.out.println("我是紅旗");
}
}
package com.jdk8new.defau;
public class CarImpl implements Car1,Car2 {
@Override
public void print() {
Car1.super.print();
}
}
2.jdk中的函數(shù)式接口
package com.jdk8new.function;
import java.util.function.*;
public class FunctionTest {
public static void main(String[] args) {
//接收兩個(gè)參數(shù)，沒(méi)有返回值
testBiConsumer();
System.out.println("---end BiConsumer------");
//接收兩個(gè)參數(shù)，返回一個(gè)參數(shù)
testBiFunction();
//BiFunction的一種特殊情況,兩個(gè)相同的入?yún)ⅲ粋€(gè)出參與入?yún)㈩?lèi)型一致
testBinaryOperation();
//返回boolean值，接收兩個(gè)參數(shù)(例如比較兩個(gè)值的大小)
testBiPredicate();
//沒(méi)有入?yún)ⅲ祷豣oolean值(例如比較兩個(gè)字符串大小)
testBooleanSupplier("1","1");
//接收一個(gè)參數(shù)，沒(méi)有返回值,適合對(duì)對(duì)象進(jìn)行加工
testConsumer();
}
private static void testConsumer() {
Consumer<User> reSetFun = u -> u.setId(u.getName());
User u = new User();
u.setId("1");
u.setName("dadfa");
reSetFun.accept(u);
System.out.println(u.getId());
}
private static void testBooleanSupplier(String a,String b) {
BooleanSupplier su = ()-> a.equals(b);
}
private static void testBiPredicate() {
//定義一個(gè)比較大小的函數(shù),a如果比b大返回true否則返回false
BiPredicate<Integer,Integer> compareFun=(a,b)-> a>b;
System.out.println(compareFun.test(1,2));
}
private static void testBinaryOperation() {
BinaryOperator<User> us1=(u1,u2)-> u1;
us1.apply(new User(),new User());
}
private static void testBiFunction() {
//此函數(shù)輸入兩個(gè)object入?yún)?，返回一個(gè)object出參
//自定義實(shí)現(xiàn)邏輯兩數(shù)相加
BiFunction<Integer,Integer,Integer> addMath=(a,b)-> a+b;
//此函數(shù)接收一個(gè)Object入?yún)?，返回一個(gè)Object出參
//自定義實(shí)現(xiàn)了對(duì)入?yún)⒃黾?倍，并返回
Function<Integer,Integer> then = a->a*2;
//此方法的執(zhí)行邏輯是，先執(zhí)行1+2 =3,再對(duì)3執(zhí)行乘以2=6
int x=addMath.andThen(then).apply(1,2);
System.out.println(x);
}
private static void testBiConsumer() {
//接收兩個(gè)Object參數(shù)，沒(méi)有返回值
BiConsumer<Integer,Integer> bb= (a, b)-> System.out.println(a+b);
//andThen的意思再一次調(diào)用
bb.andThen(bb).andThen(bb).accept(1,2);
}
}
package com.jdk8new.function;
public class User {
private String name;
private String id;
public User(){
super();
}
public User(String id, String name){
this.id=id;
this.name=name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Override
public String toString() {
return "{id:"+id+"--name:"+name+"}";
}
}
3.jdk8中l(wèi)ambda表達(dá)式
package com.jdk8new.lamda;
@FunctionalInterface
public interface IFuncInterface {
public int add(int a ,int b);
}
package com.jdk8new.lamda;
public class LambdaTest {
public static void main(String[] args) {
IFuncInterface addMath = (a,b)->a+b;
IFuncInterface subMath =(a,b)-> a-b;
System.out.println(addMath.add(1,2));
}
}
4.jdk8中方法引用
package com.jdk8new.methodref;
public interface Supp<T> {
T get();
}
package com.jdk8new.methodref;
public class Car {
public static Car create(Supp<Car> supp){
return supp.get();
}
public static void collide(final Car car){
System.out.println("colide:"+car.toString());
}
public void repar(){
System.out.println("repar:"+this.toString());
}
public void other(Car otherCar){
System.out.println("other:"+otherCar.toString());
}
}
package com.jdk8new.methodref;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MainTest {
public static void main(String[] args) {
//等價(jià)與下面的語(yǔ)法
Car car1=Car.create(new Supp<Car>() {
@Override
public Car get() {
return new Car();
}
});
//等價(jià)于
Car car2=Car.create(()->new Car());
//等價(jià)于
Car car3 = Car.create(Car::new);
List<Car> cars = Arrays.asList(car1,car2,car3);
//靜態(tài)方法調(diào)用
cars.forEach(Car::collide);
//特定類(lèi)的任意對(duì)象的方法
cars.forEach(Car::repar);
//特定對(duì)象的方法引用
Car car4=Car.create(Car::new);
cars.forEach(car4::other);
List<String> list= new ArrayList<>();
list.add("sdfsf1");
list.add("sdfsf2");
list.add("sdfsf3");
list.add("sdfsf4");
list.add("sdfsf5");
list.forEach(System.out::println);
}
}
5.jdk8中stream流
package com.jdk8new.methodref;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class MainTest {
public static void main(String[] args) {
//等價(jià)與下面的語(yǔ)法
Car car1=Car.create(new Supp<Car>() {
@Override
public Car get() {
return new Car();
}
});
//等價(jià)于
Car car2=Car.create(()->new Car());
//等價(jià)于
Car car3 = Car.create(Car::new);
List<Car> cars = Arrays.asList(car1,car2,car3);
//靜態(tài)方法調(diào)用
cars.forEach(Car::collide);
//特定類(lèi)的任意對(duì)象的方法
cars.forEach(Car::repar);
//特定對(duì)象的方法引用
Car car4=Car.create(Car::new);
cars.forEach(car4::other);
List<String> list= new ArrayList<>();
list.add("sdfsf1");
list.add("sdfsf2");
list.add("sdfsf3");
list.add("sdfsf4");
list.add("sdfsf5");
list.forEach(System.out::println);
}
}
6.jdk8中optional類(lèi)
package com.jdk8new.optional;
import java.util.Optional;
public class TestOptional {
public static void main(String[] args) {
testEmpty();
}
private static void testEmpty() {
//創(chuàng)建一個(gè)空的Optional對(duì)象
Optional<Object> empty = Optional.empty();
//創(chuàng)建一個(gè)值為Integer=10的Optional對(duì)象
Optional<Integer> pi = Optional.of(10);
Optional<Integer> p2 = Optional.of(10);
//判斷optional對(duì)象中是否存在值
System.out.println(empty.isPresent());
//Optional對(duì)象中如果有值，調(diào)用ifPresent方法定義的函數(shù)式接口自定義邏輯
pi.ifPresent(System.out::println);
//創(chuàng)建一個(gè)值可以為null的Optional對(duì)象
Optional<Integer> inter = Optional.ofNullable(11);
inter.ifPresent(System.out::println);
//獲取Optional對(duì)象中的值，如果不存在，返回參數(shù)other
Integer integer = pi.orElse(12);
System.out.println(integer);
Object o = empty.orElse(13);
System.out.println(o);
//獲取Optional對(duì)象中的值，如果不存在，返回接口自定義邏輯中的值
Object o1 = empty.orElseGet(() -> 10);
System.out.println(o1);
System.out.println(pi.equals(p2));
}
}
