https://player.bilibili.com/player.html?aid=55895675

    递归方法

    1. package bigdata215.week16_3_1;
    2. //递归方法
    3. public class Sum {
    4.     public stati
    5. c int count(int n){
    6.         if(n>1){
    7.             return count(n - 1)+ n;
    8.         } else{
    9.             return n;
    10.         }
    12.         }
    13.     public static void mian(String[] args){
    14.         System.out.println(Sum.count(100));
    15.     }
    16. }
    1. package bigdata215.week16_3_1;
    3. public class Week16_3_4 {
    4.     public static void main(String[] args) {
    5.         //各种类型的数组，数组的长度与格式(类型)不可变，数组初始化一定要确定长度
    6.         int[] arr1={1,5,7};//静态初始化，整数数组
    7.         double[] arr2={1.2,4.6};//小数类型数组
    8.         String[] arr3={"hello","world"};//
    9.         char[] arr4={'a','b'};
    10.         boolean[] arr5={true,false};
    11.         Student s1 = new Student("张三",5);
    12.         Student s2= new Student("lisi",8);
    13.         //学生数组
    14.         Student[] arr6={s1,s2};
    15.         System.out.println(arr6[0].toString());
    16.         System.out.println(arr6[0]);//默认的toString()，如果不加上tostring，打印出的值是哈希值而不是属性值
    17.     }
    18. }
    19. class Student{
    20.     String name;
    21.     int age;
    22.     public Student(String name,int age){
    23.         this.name=name;
    24.         this.age=age;
    25.     }
    26.     @Override
    27.     public String toString(){
    28.         return name+" "+age;
    29.     }
    30. }

    作业
    定义一个数组 反向遍历