使用沿X，Y，Z轴线的数据创建Apache POI Excel

Question

I'm working on creating an excel using XSSF.

This excel will contain data in the top 3 rows (Imagine this as x axis). I also have data filled in 2 left hand columns (Imagine this as Y axis).

Now, i have to add a flag across the sheet indicating a match between x & y axis values (Imagine z axis).

Eg if i have values on x axis: x1 (Cell:D1),x2,x3,x4 etc... on Y axis: Y1, Y2, Y3(Cell:12C) )etc.

If x1 == Y3, I have a mark the common cell (D12) with 'X'.

I have all this data in Linkedhashmap's. X-axis data in one linkedhashmap, y-axis in another and i also have the information, which x values equals to which y value in another linkedhashamp. So i have to loop over these hashmaps and create an excel sheet.

My question : I have this matching info hashmap with column (x-axis) data as Key and Row data as values. So, i have to traverse the sheet column wise. (X1->Y3,Y100,Y123, X2->Y2,Y79,Y500).

Is this good approach or Should i reverse the key and values in the hasmap, Considering performance ?

I have limited (ranging:100-5000) values on x-axis (the reason for keep them on x-asixs) while i have 1 million rows/values (on Y-axis).

Open to any other suggestions you may have, please suggest.

Thanks a lot for your help.

PS I have experience working with excel and also a bit of experience working with POI, I know the basics and i have created excel sheets before but with limited data and which always goes row wise and not like this multidimensional.

Answer 1

I think I would use

cell.setCellFormula(formula_str);

with a formula like

=if(a1=b3, "", "MISMATCH") 

or however its supposed to work. That way you let Excel do the work rather than having to make hashmaps and all kinds of convoluted things in your Java code. Also that way, when a user updates the Excel it will update for them. Users won't like it if your calculations don't update when they change the data in Excel.

cell.setCellFormula("IF(A1=B3, \"\", \"MISMATCH\")");

To create your column or row of forumulas you just need a loop to change the numbers from A1, B3 to whatever as you traverse and add the formula cells.