I have run the following Java code:

import java.util.*;
public class Main {

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

}

Output is the following:

1 7 3
1 7 3
1 7 3

But my expectation was:

1 2 3
1 7 3
1 2 3

Why does this happen?