Refer To Arrays Dynamically Java

Question

I have a series of arrays in my Java program

Integer[] row1 = {0,0,0,0,0,0};
Integer[] row2 = {0,0,0,0,0,0};
Integer[] row3 = {0,0,0,0,0,0};
Integer[] row4 = {0,0,0,0,0,0};
Integer[] row5 = {0,0,0,0,0,0};
Integer[] row6 = {0,0,0,0,0,0};

I also have a randomly generated number between 1-6:

    int selectrow = rand.nextInt(6)+1;

I need to refer to each of those rows based on the value of the generated number. So something like "row" + selectrow and then do something to it, but I am not sure how to achieve this without if statements. If statements would just get too messy. Any ideas?

You could but you really really shouldn't. Build an array of arrays, or another structure, don't try to access variables by name. — Denys Séguret, Jun 01 '15 at 14:24
@DenysSéguret how we could access variable with their names in run time? using reflection? — Lrrr, Jun 01 '15 at 14:26
Alright Denys, I trust you, I'll just make the array of arrays :) — user3124181, Jun 01 '15 at 14:28
Good. Please use also loops to fill your matrix ;) And use int, not Integer, if you have no reason to use objects — Denys Séguret, Jun 01 '15 at 14:28

score 1 · Accepted Answer · answered Jun 01 '15 at 14:32

Build an array of arrays.

And use int, not Integer, unless you have a very specific reason for using expensive objects.

And use loops to fill your matrix. Unless you fill it with 0 and use int, because, well, it's the default value.

All in one, here's what your code could be like:

    int[][] matrix = new int[6][6];
    Random rand = new Random();
    // there's probably something happening here
    int[] selectedRow = matrix[rand.nextInt(6)];

score 0 · Answer 2 · answered Jun 01 '15 at 14:27

0

You should work with an array of arrays:

Integer[][] rows = createRows();
int selectrow = rand.nextInt(6);
Integer[] = rows[selectrow];

Note that I removed the +1 part in the initialization of variable selectrow. Arrays in Java have 0-based indexes.

answered Jun 01 '15 at 14:27

Seelenvirtuose

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score 0 · Answer 3 · edited May 23 '17 at 12:30

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Instead of using separate variables for each row, you're almost always better off using a two-dimensional array instead. Selecting a new row is trivial then:

Integer[] row = rows[rand.nextInt(6)];

(Note that indices start at 0, not 1.)

edited May 23 '17 at 12:30

Community

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answered Jun 01 '15 at 14:27

DarkDust

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score 0 · Answer 4 · answered Jun 01 '15 at 14:29

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Add them to an array of arrays:

Integer[][] arrays = { row1, row2, row3, row4, row5, row6 };
Integer[] row = arrays[selectRow];

answered Jun 01 '15 at 14:29

folkol

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Refer To Arrays Dynamically Java

4 Answers4