Comparator接口和Comparable接口

   以下是我个人对这两个接口的理解

   首先是这两个接口的共性，这两个接口的实现都可以实现类与类之间的比较，也能将一个类的数组进行排序。

   1.Comparable接口，通过implements实现该接口代表该类具有比较功能，通过重写compareTo方法来设置这个类默认的比较方法，一但设置成功，后续修改风险非常大

class Student implements Comparable<Student>{
    public String name;
    public int age;
    public Student(String name,int age){
        this.name = name;
        this.age = age;
    }

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

    //通过Comparable设置一个默认类比较器
    @Override
    public int compareTo(Student o) {
       return this.age-o.age;
//        return this.name.compareTo(o.name);
    }
}
public class Main {
    public static void main(String[] args) {
        Student[] arr = new Student[3];
        arr[0] = new Student("liu",20);
        arr[1] = new Student("zhang",18);
        arr[2] = new Student("wang",23);
        System.out.println(Arrays.toString(arr));
        System.out.println("==================");
        Arrays.sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

 2.Comparator接口，该接口的实现需要是额外再定义一个类作为比较器

class Student{
    public String name;
    public int age;

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
    public Student(String name,int age){
        this.age  = age;
        this.name = name;
    }
}
           //年龄比较器
class Add implements Comparator<Student>{

    @Override
    public int compare(Student o1, Student o2) {
        return o1.age-o2.age;
    }
}
             //姓名比较器
class Bdd implements Comparator<Student>{

    @Override
    public int compare(Student o1, Student o2) {
        return o1.name.compareTo(o2.name);
    }
}
public class Main {
    public static void main(String[] args) {
                                     /* 正常数据直接比较 */
        Student student1 = new Student("da",18);
        Student student2 = new Student("wa",15);
        Add a = new Add();
        int num1 = a.compare(student1,student2);
        Bdd b = new Bdd();
        int num2 = b.compare(student1,student2);
        System.out.println(num1);
        System.out.println(num2);
        Student[] arr = new Student[3];
        arr[0] = new Student("liu",20);
        arr[1] = new Student("zhang",18);
        arr[2] = new Student("wang",23);
                                     /* 数组排序 */
        System.out.println(Arrays.toString(arr));
        //指定比较器
        Arrays.sort(arr,a);
        System.out.println("==========");
        System.out.println(Arrays.toString(arr));
    }
}