How to create a random boolean 2D array with a specific number of true?

Question

I am trying to create a minesweeper game and for the randomisation part I am having some trouble.

For perhaps a 10 by 10 grid minesweeper, I hope to achieve 10 or a specific number of bombs/mines randomly but am unsure of how to do it.

I have a 2D mines array that stores TRUE if it contains a bomb.

I know in a 1D array I could have the total number of elements divided up into n equal parts and then have one TRUE boolean element per part.

Ah, but it doesn't have to be equally distributed. I am also not very sure about lists, would using a list be a good way to solve this?

Answer 1

final int GRID_WIDTH = 10;
final int GRID_HEIGHT = 10;
final int BOMB_NUMBER = 10;
final boolean[][] minesArray = new boolean[GRID_WIDTH][GRID_HEIGHT];
for (int i = 0; i < BOMB_NUMBER; i++) {
     //Get random position for the next bomb
     Random rand = new Random();
     int row = rand.nextInt(GRID_WIDTH);
     int col = rand.nextInt(GRID_HEIGHT);
     while(minesArray[row][col]) { //if this position is a bomb
          //we get new position
          row = rand.nextInt(GRID_WIDTH);
          col = rand.nextInt(GRID_HEIGHT);
     }
     minesArray[row][col] = true; //make new position is a bomb
}