jdk8-方法引用

方法引用的形式

方法引用的标准形式是:类名::方法名。（注意：只需要写方法名，不需要写括号）

有以下四种形式的方法引用:

类型 示例

引用静态方法 ContainingClass::staticMethodName

引用某个对象的实例方法 containingObject::instanceMethodName

引用某个类型的任意对象的实例方法 ContainingType::methodName

引用构造方法 ClassName::new

下面我们通过一个小Demo来分别学习这几种形式的方法引用:

Student 类：

public 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;
}

public static int coompareStudentByScore(Student student1,Student student2){
return student1.getScore() - student2.getScore();
}

public static int coompareStudentByName(Student student1,Student student2){
return student1.getName().compareToIgnoreCase(student2.getName());
}

public int compareScore(Student student){
return this.score-student.getScore();
}

}

StudentComparator 比较器：

public class StudentComparator {

public  int coompareStudentByScore(Student student1,Student student2){
return student1.getScore() - student2.getScore();
}

public  int coompareStudentByName(Student student1,Student student2){
return student1.getName().compareToIgnoreCase(student2.getName());
}

}

测试类：MethodReferenceTest

* Created by CeaserWang on 2017/1/15.
*/
public class MethodReferenceTest {

public String toString(Supplier<String> supplier){
return supplier.get()+"test";
}

public String toString2(String str, Function<String,String> function){
return function.apply(str);
}

public static void main(String[] args) {
Student student1   = new Student("zhangsan",20);
Student student2   = new Student("lisi",90);
Student student3   = new Student("wangwu",50);
Student student4   = new Student("zhaoliu",60);

List<Student> students = Arrays.asList(student1,student2,student3,student4);
//lambda形式
students.sort((studentparam1,studentparam2) -> Student.coompareStudentByName(studentparam1,studentparam2));
students.forEach(student -> System.out.println(student.getName()));*/
// 引用静态方法
/* students.sort( Student::coompareStudentByName);
students.forEach(student -> System.out.println(student.getName()));

System.out.println("----------------------------------------------");

//引用某个对象的实例方法
StudentComparator studentComparator = new StudentComparator();
students.sort(studentComparator::coompareStudentByScore);
students.forEach(student -> System.out.println(student.getScore()));

System.out.println("----------------------------------------------");

//引用某个类型的任意对象的实例方法
students.sort(Student::compareScore);
students.forEach(student -> System.out.println(student.getScore()));
MethodReferenceTest methodReferenceTest =  new MethodReferenceTest();
//引用构造方法
System.out.println( methodReferenceTest.toString(String::new));
System.out.println( methodReferenceTest.toString2("hello",String::new));
}
}