for loop for the two-dimentional String array

Mohsen :

I want to have the following outcome:

enter image description here

and i was writing the following code for this purpose:

String[][] teamView = new String[24][35];
    int [] numbers = new int[]{};
    int k =1;
    for(int i=0; i< 24; i++)
    {

        for(int j = 0 ; j< 35; j++)
        {
            if (j == 0 && i==0){teamView[i][j] = "@";}
            else if(j==0){ teamView[i][j] += (char)(i + 64) ;}
            else if (j==1){teamView[i][j] = " " ;}
            else if (i ==0 ){
                switch (j){
                    case 3:
                        teamView[i][j] = "1" ;
                        break;
                    case 6:
                        teamView[i][j] = "2" ;
                        break;
                    case 9:
                        teamView[i][j] = "3" ;
                        break;
                    case 12:
                        teamView[i][j] = "4" ;
                        break;
                    case 15:
                        teamView[i][j] = "5" ;
                        break;
                    case 18:
                        teamView[i][j] = "6" ;
                        break;
                    case 21:
                        teamView[i][j] = "7" ;
                        break;
                    case 24:
                        teamView[i][j] = "8" ;
                        break;
                    case 27:
                        teamView[i][j] = "9" ;
                        break;
                    case 30:
                        teamView[i][j] = "10" ;
                        break;

                }

            }else if (i ==0){teamView[i][j] = " ";}else


            teamView[i][j] = "#";
            System.out.print(teamView[i][j]);
        }
        System.out.print("\n");

    }

but the problem is that now i get null in-between the numbers in the first row, also before the letters in the first column. why do i get these nulls in the print? how can i improve my loops?

it is about the battleship game in EDX(https://courses.edx.org/courses/course-v1:PurdueX+CS180.4x+1T2020a/courseware/7e1459f3e5be4579b645cf16c4196954/a030e2346c374159b8875682791e1606/3?activate_block_id=block-v1%3APurdueX%2BCS180.4x%2B1T2020a%2Btype%40lti_consumer%2Bblock%408338de93e7c3499688734a1469b4eca9) , if anyone have an idea please help me, thank you.

B.Mik :

The nulls at the first line are happening because you have 2 repeated conditional statements if (i == 0) and the other nulls on each line are happening because you are concatenating the char with the string using += which is giving nullA etc so instead do this:

String[][] teamView = new String[24][35];
        for (int i = 0; i < teamView.length; i++)
        {
            for (int j = 0; j < teamView[i].length; j++)
            {
                if (j == 0 && i == 0)
                {
                    teamView[i][j] = "@";
                } else if (j == 0)
                {
                    teamView[i][j] = String.valueOf((char) (i + 64)) ;  // the nulls on each line fix
                } else if (j == 1)
                {
                    teamView[i][j] = " ";
                } else if (i == 0 && j % 3 == 0)   //instead of the only i == 0 check its a multiple of 3
                {
                    teamView[i][j] = String.valueOf(j / 3);  //instead of the switch you can just divide the j by 3 if it's is a multiple of 3
                } else if (i == 0)
                {
                    teamView[i][j] = " ";
                } else
                    teamView[i][j] = "#";
                System.out.print(teamView[i][j]);
            }
            System.out.print("\n");
        }
    }

Output

@  1  2  3  4  5  6  7  8  9  10  11 
A #################################
B #################################
C #################################
D #################################
E #################################
F #################################
G #################################
H #################################
I #################################
J #################################
K #################################
L #################################
M #################################
N #################################
O #################################
P #################################
Q #################################
R #################################
S #################################
T #################################
U #################################
V #################################
W #################################