打印输出换行

public static void main(String[] args) {
    int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9};
    for (int i = 0; i < arr.length; i++) {
        if (i % 3 == 0) {
            System.out.println();
        }
        if (arr[i] % 3 == 0) {
            System.out.print(arr[i]);
        } else {
            System.out.print(arr[i] + ", ");
        }
    }
}