Creating Two-Dimensional String Array for Plane Seats
Here are a few optimization suggestions:

You can get rid of alphabetPos because it is always equals to i.
In fact, while you are at it, your code will be more readable if you rename i to row and j to col or column.

You can also get rid of columnToString and just rely on Java's string concatenation overloads.


 seatArray[i][j-1] = alphabet[alphabetPos] + j;

Note that you use j multiple times as index, subtracting one, and only once as string.
It would make your code more readable if you used zero based index, and only added 1 for the string composition.

You may want to use string formatting.



for (int col = 0; col &lt; this.getNumOfColumns(); col++) {
        seatArray[row][col] = String.format(&quot;%s%d&quot;, alphabet[row], col + 1);

        if (this.getNumOfColumns() == 4) {
            if (col == 1) {
                System.out.print(seatArray[row][col] + &quot;       &quot;);
            } else {
                System.out.print(seatArray[row][col] + &quot; &quot;);
            }
        } else {
            if (col == 2) {
                System.out.print(seatArray[row][col] + &quot;       &quot;);
            } else {
                System.out.print(seatArray[row][col] + &quot; &quot;);
            }
        }
}


You can simplify your array printing by splitting it in to two parts: printing the seat number and printing the spacer.
The first part is always the same, so no need to repeat it 4 times.
The second part changes only when col and row have certain values, so one condition is enough.


System.out.print(seatArray[row][col] + &quot; &quot;); //this part is always printed the same

//just add a few more spaces if this is an isle seat
if ((getNumOfColumns() == 4 &amp;&amp; col == 1) || (getNumOfColumns() != 4 &amp;&amp; col == 2)) {
    System.out.print(&quot;      &quot;);
}


Finally, to save memory, you can get rid of the alphabet array all together, since the seat letters are sequential and rows 26 and above just have the same letter twice:


String rowStr = String.format(&quot;%c&quot;, 'a' + (row % 26));
if (row &gt; 25) rowStr += rowStr;
seatArray[row][col] = String.format(&quot;%s%d&quot;, rowStr, col + 1);