方法引用

方法引用概述 优化lambda表达式

方法引用概述

package com.mujiachao.fangfayinyong;
@FunctionalInterface
public interface PrintTest {
    void print1(String s);
}

package com.mujiachao.fangfayinyong;

public class Demo1 {
    public static void printTest(PrintTest p){
        p.print1("方法引用");
    }

    public static void main(String[] args) {
        printTest(System.out::println);
    }
}

通过对象名引用成员方法

通过对象名引用成员方法

package com.mujiachao.fangfayinyong;
@FunctionalInterface
public interface PrintTest {
    void print1(String s);
}

package com.mujiachao.fangfayinyong;

public class Method {
    public void get(String s){
        System.out.println(s.toUpperCase());
    }
}

package com.mujiachao.fangfayinyong;

public class Demo2 {
    public static void printTest(PrintTest p){
        p.print1("mujiachao");
    }
    public static void main(String[] args) {
        Method method = new Method();
        printTest(method::get);
    }
}

通过类名引用静态成员方法

通过类名引用静态成员方法

package com.mujiachao.fangfayinyong;
@FunctionalInterface
public interface PrintTest1 {
    int print2(int s);
}

package com.mujiachao.fangfayinyong;

public class Demo3 {
    public static int printTest(int a,PrintTest1 p) {
      return  p.print2(a);
    }

    public static void main(String[] args) {

        int i = printTest(-8, Math::abs);
        System.out.println(i);
    }
}

通过super引用父类的成员方法

通过super引用父类的成员方法

package com.mujiachao.fangfayinyong;
@FunctionalInterface
public interface Greetable {
    void greet();
}

package com.mujiachao.fangfayinyong;

public class SuperMan {
   public void say(){
       System.out.println("我的名字是 ：superm");
   }
}

package com.mujiachao.fangfayinyong;

public class Man extends SuperMan{

    @Override
    public void say() {
        System.out.println("我的名字是： man");
    }
    public  void method(Greetable g){
        g.greet();
    }
    public void show(){
        method(super::say);
    }

    public static void main(String[] args) {
          new Man().say();
          new Man().show();

    }
}

通过this关键字引用本类的成员方法

package com.mujiachao.fangfayinyong;

public class Man extends SuperMan{

    @Override
    public void say() {
        System.out.println("我的名字是： man");
    }
    public  void method(Greetable g){
        g.greet();
    }
    public void show(){
        method(super::say);
    }

    public static void main(String[] args) {
          new Man().say();
          new Man().show();

    }
}

package com.mujiachao.fangfayinyong;

public class Husband {
    public void buyFang(){
        System.out.println("买了一辆宝马车");
    }
    public void buyToo(Buyable b){
        b.buy();
    }
    public void maary(){
        buyToo(this::buyFang);
    }

    public static void main(String[] args) {
        new Husband().maary();
    }
}

类的构造器引用

package com.mujiachao.fangfayinyong;

public class Person {
    private String name;

    public Person() {
    }

    public Person(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

package com.mujiachao.fangfayinyong;
@FunctionalInterface
public interface PersonBuilder {
    Person getPerson(String name);
}

package com.mujiachao.fangfayinyong;

public class TestPerson {
    public static void getP(String name,PersonBuilder p){
        Person person = p.getPerson(name);
        System.out.println(person.getName());
    }

    public static void main(String[] args) {
        getP("捷克隽逸",name -> new Person(name));
        getP("古力娜扎",Person::new);
    }
}

数组的构造器引用

package com.mujiachao.fangfayinyong;

public interface ArrayBuilder {
    int[] getArray(int len);
}

package com.mujiachao.fangfayinyong;

public class DemoArray {
    public  static  void gerArrayLength(int len,ArrayBuilder arrayBuilder){
        int[] array = arrayBuilder.getArray(len);
        System.out.println(array.length);
    }

    public static void main(String[] args) {
        gerArrayLength(201,int[]::new);
    }
}