Java8 MethodReference方法引用

package com.lgx.jdk8.part02;import java.util.Arrays;import java.util.Collections;import java.util.List;import java.util.function.Function;import java.util.function.Supplier;/** * 方法引用的学习 */public class Test02MethodReference {    public String getString(Supplier<String> supplier){        return supplier.get() + "test";    }    public String getString2(String str, Function<String, String> function){        return function.apply(str);    }    public static void main(String[] args) {        List<String> list = Arrays.asList("hello", "world", "hello world");        //之前学习Lambda的写法        list.forEach(item -> System.out.println("item = [" + item + "]"));        //方法引用的写法        list.forEach(System.out::println);        //方法引用共分为4类：        //a、类名::静态方法名        //当你使用的Lambda表达式恰好有一个静态方法可以完成，则可以使用这种方式        Student student1 = new Student("zhangsan", 60);        Student student2 = new Student("lisi", 80);        Student student3 = new Student("wangwu", 50);        Student student4 = new Student("zhaoliu", 78);        List<Student> studentList = Arrays.asList(student1, student2, student3, student4);        //studentList.sort((studentPara1, studentPara2) -> Student.compareStudentsByScore(studentPara1, studentPara2));//传统写法        /*studentList.sort(Student::compareStudentsByScore);        studentList.forEach(student -> System.out.println("student = [" + student.getScore() + "]"));        //b、引用名(对象名)::实例方法名        /*studentList.sort(new StudentComparator()::compareStudentsByScore);        studentList.forEach(student -> System.out.println("student = [" + student.getScore() + "]"));*/        //c、类名::实例方法名        //与上面那个类似，Lambda表达式传递进来的第一个参数作为当前对象，当作调用者，        //第二及以后的参数才传递给被调用的方法        /*studentList.sort(Student::compareByScore);        studentList.forEach(student -> System.out.println("student = [" + student.getScore() + "]"));        studentList.sort(Student::compareByName);        studentList.forEach(student -> System.out.println("student = [" + student.getName() + "]"));*/        //拓展下        List<String> cites = Arrays.asList("jiangxi", "hubei", "shenzhen", "beijing");        //Collections.sort(cites, (city1, city2) -> city1.compareTo(city2));//传统写法        //cites.forEach(city -> System.out.println("city = [" + city + "]"));//传统写法        Collections.sort(cites, String::compareTo);//这里是第3种写法        cites.forEach(System.out::println);//这里是第2种写法        //d、类名::new        //也叫构造方法引用        Test02MethodReference test = new Test02MethodReference();        String result = test.getString(String::new);        System.out.println("result = [" + result + "]");        String result2 = test.getString2("hello", String::new);        System.out.println("result2 = [" + result2 + "]");    }}class Student{    private String name;    private int score;    public Student(String name, int score) {        this.name = name;        this.score = score;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getScore() {        return score;    }    public void setScore(int score) {        this.score = score;    }    //按照学生的成绩对学生进行排序    public static int compareStudentsByScore(Student student, Student student2){        return student.getScore() - student2.getScore();    }    //按照学生的名字对学生进行排序    public static int compareStudentsByName(Student student, Student student2){        return student.getName().compareTo(student2.getName());    }    //按照学生的成绩对学生进行排序    public int compareByScore(Student student){        return this.getScore() - student.getScore();    }    //按照学生的名字对学生进行排序    public int compareByName(Student student){        return this.getName().compareTo(student.getName());    }}class StudentComparator{    //按照学生的成绩对学生进行排序    public int compareStudentsByScore(Student student, Student student2){        return student.getScore() - student2.getScore();    }    //按照学生的名字对学生进行排序    public int compareStudentsByName(Student student, Student student2){        return student.getName().compareTo(student2.getName());    }}