public void shift(String dir, int row, int col) {
		switch (dir) {
		case "up":
			for (int r = row; r < 3; r ++) 
				BOARD[r][col] = BOARD[r+1][col];
			BOARD[3][col] = 0; //set last one to 0 because all others have been shifted
			break;
		case "down":
			for (int r = row; r > 0; r --) 
				BOARD[r][col] = BOARD[r-1][col];
			BOARD[0][col] = 0; //set last one to 0 because all others have been shifted
			break;
		case "left":
			for (int c = col; c < 3; c ++) 
				BOARD[row][c] = BOARD[row][c+1];
			BOARD[row][3] = 0; //set last one to 0 because all others have been shifted
			break;
		case "right":
			for (int c = col; c > 0; c --) 
				BOARD[row][c] = BOARD[row][c-1];
			BOARD[row][0] = 0; //set last one to 0 because all others have been shifted
			break;
		default:
			System.out.println("in shift method, input needs to be up, down, left or right");
		}
	}