10-方法引用

类型或对象::引用的方法  //关键语法  “::”

package ComparatorDemo;

import java.util.ArrayList;
import java.util.List;

public class MethodDemo {
    public static void main(String[] args) {
        List<String> lists=new ArrayList<>();
        lists.add("first");
        lists.add("second");
        lists.add("third");
        //遍历列表，通过Lambda表达式的方法
        lists.forEach(s -> System.out.println(s));
        
        //方法引用(前提：必须形如上式前后的参数一致)
        lists.forEach(System.out::println);
    }
}

类名::静态方法

//首先定义静态方法
public static int compareByAge(Student s1,Student s2){
    return s1.getAge()-s2.getAge();
}

package ComparatorDemo;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class ComparatorDemo1 {

    public static void main(String[] args) {
        List<Student> lists=new ArrayList<>();
        Student s1=new Student("Leslie",18,"Man");
        Student s2=new Student("John",14,"Man");
        Student s3=new Student("Gym",20,"Woman");
        //批量向数组插入数据
        Collections.addAll(lists,s1,s2,s3);
        //按照年龄进行排序(匿名内部类做法)
        Collections.sort(lists, (t1,t2)->Student.compareByAge(t1,t2));
        //使用静态方法进行简化,前后参数必须相同
        Collections.sort(lists,Student::compareByAge);

        for(Student stu:lists) {
            System.out.printf("name=%s age=%d sex=%s\n",stu.getName(),stu.getAge(),stu.getSex());
        }
    }
}

对象::实例方法

类名::new 

//前后参数一致，并在创建对象
s -> new Student(s);
//改写成引用
Student::new