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javaarrays
J. Smith
J. Smith

Reputation: 17

Print A 2D Array As A Grid? (Java)

I've run into a bit of a conundrum in a personal Java project I've been working on. I want to print a two-dimensional array of Strings in the form of a table. Not the Strings by themselves, but with row and column labels as well (think Microsoft Excel). This is what I envision the finished product to be, with asterisks representing where the Strings should go.

    |    A    |    B    |    C    |    D    |    E    |    F    |    G    |
----+---------+---------+---------+---------+---------+---------+---------+
  1 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  2 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  3 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  4 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  5 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  6 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  7 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  8 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
  9 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+
 10 |    *    |    *    |    *    |    *    |    *    |    *    |    *    |
----+---------+---------+---------+---------+---------+---------+---------+

I know that this will use a nested forward loop, and that the logical process would be to put the String values in the inner loop, like "example[i][j]" type format. I'm just so confused as to how I go about getting the design around the cells in the right format, limiting each String to 10 characters like how Excel limits their cell size when shrunken down. Do I use substring for that? Do I use printf to get the 10th row correctly spaced?

Any pointers are greatly appreciated, I've never been stumped quite like this before.

Upvotes: 0

Views: 6376

Answers (2)

Bagelman
Bagelman

Reputation: 766

public static void printStringGrid(String[][] array){
    System.out.print("    |");
    for (int i = 0; i < array[0].length; i++){
        System.out.print("    ");
        System.out.print((char)('A' + i));
        System.out.print("    |");
    }
    System.out.println();
    for (int i = 0; i < array.length; i++){
        System.out.print("----+");
        for (int j = 0; j < array[0].length; j++){
            System.out.print("---------+");
        }
        System.out.println();
        System.out.print("  " + (i + 1) + " |");
        for (int j = 0; j < array[0].length; j++){
            if (array[i][j].length() < 10){
                int spaces = (9 - array[i][j].length()) / 2;
                for (int k = 0; k < spaces; k++){
                    System.out.print(" ");
                }
                System.out.print(array[i][j]);
                for (int k = 0; k < (9 - array[i][j].length()) - spaces; k++){
                    System.out.print(" ");
                }
            }
            else{
                System.out.print(array[i][j].substring(0, 9));
            }
            System.out.print("|");
        }
        System.out.println();
    }
}

Upvotes: 1

Andreas
Andreas

Reputation: 159086

The first line should be easy enough, assuming you don't exceed 26 columns, i.e. column name is just A to Z.

The even lines are all a lead-in of ----+, followed by columnCount repeats of ---------+.

The odd lines (except first), are a lead-in of 999 |, where 999 is a row number, right-justified, with leading spaces. That can be done with printf() or String.format() with a format string of
"%3d |".

Following the lead-in are columnCount repeats of a string value, trimmed and center-aligned to 9 characters, followed by a |.

To center-align to 9 characters, do the following:

  • If length > 9, trim to 9 (yes, using substring()).
  • Otherwise, calculate spaces needed, i.e. spacesTotal = 9 - trimmedLength.
    Calculate spaces on left: spaceBefore = spacesTotal / 2.
    Calculate spaces on right: spaceAfter = spacesTotal - spaceBefore.
    By doing it that way, an odd number of spaces such as 5, becomes 2 before and 3 after.
    Now print spaceBefore spaces, the (trimmed) text value, then spaceAfter spaces, and a |.

Upvotes: 1

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