Comparable接口和Comparator接口实现数组排序

（1）要求对象数组的元素实现java.lang.Comparable接口，即支持比较大小。元素重写的int compareTo（Object obj)指定按照什么排序，就怎么排序

（1）给对象数组传一个java.util.Comparator接口的实现类对象，重写的int compare(Object o1, Object o2)方法中指定排序的规则

public void test15() {
        Student[] arr = new Student[3];
        arr[0] = new Student(1,"张三",23,89);
        arr[1] = new Student(2,"宋鑫",22,100);
        arr[2] = new Student(3,"牛钰琪",20,90);

        //按照年龄，年龄相同，就按照学号排序
        Arrays.sort(arr, new Comparator(){
                    @Override
                    public int compare(Object o1, Object o2) {
                        Student s1 = (Student) o1;
                        Student s2 = (Student) o2;
                        int result = s1.getAge() - s2.getAge();
                        if(result != 0){
                            return result;
                        }
                        return s1.compareTo(s2);//Student类中实现的compareTo方法是按照学号排序
                    }
                }
        );

        System.out.println(Arrays.toString(arr));
    }