Java CompareTO 方法问题

Question

我正在尝试用一个简单的java程序整理一个简单的学生标记列表，但是我得到了

Exception in thread "main" java.lang.ClassCastException: Student cannot be cast to java.lang.Comparable

public class Student {
public String name;
public int mark;


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


public int compareTo(Student o){
    return this.mark-o.mark;


}
public String toString(){
    String s = "Name: "+name+"\nMark: "+mark+"\n";
    return s;
}

public static void main(String[] args) {
    Student Class[] = new Student[9];
    Class[0] = new Student("Henry",100);
    Class[1] = new Student("Alex", 10);
    Class[2] = new Student("Danielle",100);
    Class[3] = new Student("Luke",10);
    Class[4] = new Student("Bob",59);
    Class[5] = new Student("Greg",76);
    Class[6] = new Student("Cass",43);
    Class[7] = new Student("Leg",12);
    Class[8] = new Student("Bobe",13);



    Arrays.sort(Class);
    for(int i = 0;i<Class.length;i++){
        System.out.println(Class[i]);

Answer 1

您的 Student 类必须实现 Comparable 接口(interface)才能使用 Arrays#sort 传递 Student[] 数组。您的类当前具有 compareTo 方法这一事实并不意味着它实现了此接口(interface)，您必须声明:

public class Student implements Comparable<Student> {
    //class definition...
}