JDK1.8方法引用

创建实体

public class Student {

    private String name;
    private int age;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Student() {
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    public static int compareAge(Student s1,Student s2){
        return s1.getAge() - s2.getAge();
    }

    public static int compareName(Student s1,Student s2){
        return s1.getName().compareTo(s2.getName());
    }

    public int compareByAge(Student s1){
        return this.getAge() - s1.getAge();
    }

    public int compareByName(Student s1){
        return this.getName().compareTo(s1.getName());
    }

    public void sout(){
        System.out.println("sout");
    }

    public String returnName(){
        return this.getName();
    }
    
    public void soutTwo(Student s1){
        System.out.println(this);
        System.out.println(s1);
    }
}

工具类

public class StudentCompareUtil {

    public int compareAge(Student s1, Student s2){
        return s1.getAge() - s2.getAge();
    }

    public int compareName(Student s1,Student s2){
        return s1.getName().compareTo(s2.getName());
    }
}

方法引用

public class MethodReference {

    public static void main(String[] args) {

        List<Student> list = Arrays.asList(new Student("zhangsan",46),new Student("lisi",52),
                new Student("wangwu",12),new Student("zhaoliu",99));
        System.out.println(list);
        /**
         * 方法引用：
         * 1、类名::静态方法名
         */

        list.sort((o1, o2) -> Student.compareAge(o1, o2));
        System.out.println(list);

        list.sort(Student::compareAge);
        System.out.println(list);

        /**
         * 方法引用
         * 2、引用名(对象的引用)::实例方法名
         */

        StudentCompareUtil util = new StudentCompareUtil();

        list.sort((o1, o2) -> util.compareName(o1, o2));
        System.out.println(list);

        list.sort(util::compareName);
        System.out.println(list);

         /**
         * 方法引用
         * 方法引用示例1、2相对来说还是比较容易理解，类似以前的:类名.静态方法名、引用名.实例方法名
         * 实例3 类名::实例方法名,相当于我们自定义方法来实现某个函数式接口
         *
         * 3、类名::实例方法名
         */

        list.sort(Student::compareByAge);
        System.out.println(list);
        Comparator<Student> compareByAge = Student::compareByAge;
        Consumer<Student> sout = Student::sout;
        Function<Student, String> returnName = Student::returnName;
        BiConsumer<Student, Student> soutTwo = Student::soutTwo;
        
        /**
         * 方法引用
         * 4、构造方法引用
         */

        MethodReference methodReference = new MethodReference();
        Student student = methodReference.createStudent(Student::new);
        System.out.println(student);
        
    }

    public Student createStudent(Supplier<Student> supplier){
        return supplier.get();
    }
}