Java中的数组的问题,不太懂这个

从键盘输入元素创建一个整形数组{1, 3,6,9},并遍历打印每个元素。

public static void main(String[] args) {
        Scanner sc= new Scanner(System.in);
        int a[]=new  int[4];
        for (int i = 0; i < 4; i++) {
            a[i]=sc.nextInt();
        }
        for (int i = 0; i < 4; i++) {
            System.out.println("第"+(i+1)+"个元素是:"+a[i]);
        }
    }
Scanner scanner= new Scanner(System.in);
int n=scanner.nextInt();
int[] arr = new int[n];
for(int i=0;i<n;i++){
     arr[i] =scanner.nextInt();
}
for(int j=0;j<n;j++){
    System.out.println(arr[i]);
}


```


import java.util.*;
public class Test {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("输入数组长度:");
        int n = input.nextInt();
        int[] a = new int[n];
        System.out.print("输入数组数字:");
        for(int i=0;i<n;i++){
            a[i] = input.nextInt();
        }
        for(int i=0;i<n;i++){
            System.out.println(a[i]);
        }
    }
}