Read file line by line

Question

Hi
Could somebody tell me how to read file line by line ? Namely my input file I want to read look as follow:
AAA 1, 1
12 222 12
AAA 2, 2
11 122 11
My output file should look as follow:
1, 1, 12
1, 1 222
1, 1, 12
2, 2, 11
2, 2, 122
2, 2, 11
I think the lines need to be stored in ArrayList, then I would like those lines to write to csv file, but how on read I can construct such output file? This is my code for reading file
public ArrayList readFile(String filename)
  try
     BufferedReader in = new BufferedReader(new FileReader(filename));
     ArrayList list = new ArrayList();
     String lineS = null;
     while (in.ready())
      if ((lineS = in.readLine()).startsWith("")){
        String[] line = in.readLine().trim().split("\\s+");
        list.add(Integer.valueOf(line[0]));
        list.add(Integer.valueOf(line[1]));
        list.add(Integer.valueOf(line[2]));
     in.close();
     return list;
     catch (Exception e)
   e.printStackTrace();
return null;
Thanks

Answer 1

The rules for the conversion from input to the desired output are:
1. For each of the line with string take 2 integers for example 1, 1  from AAA 1, 1
2. Then repeat 1, 1 for each next number not containing any string, so if the line after AAA, 1, 1 has 12, 222, 12 then the output will look as follow
1, 1, 12
1, 1 222
1, 1, 12
3. Repeat the process (the pattern is the same 1 line with string 1 line with numbers)
Actually I am not sure how to perform that logic for such conversion as for now I am only able to list only the numbers but I have a problem to add numbers from the line having string in it.
STOP!
You should NOT be writing code if you are 'not sure how to perform that logic'.
You are getting ahead of yourself.
There is NOTHING to gain by trying to code a solution before you know what algorothm you need. Big mistake.
Should I use list or maybe if the patter for lines is the same array will be more sufficient?
NEITHER ONE!
Those are 'solutions' used to implelment an algorothm.
You do NOT yet know what algorithm you need to use so how can you possibly write code to implement the unknown?
How to perform logic to get the numbers from line having string and for the next lines having only numbers in order to structure it into desired output? 
THAT is the question your thread subject should have.
Until you get the answer to it don't write any code,.
Do NOT try to automate what you can't do manually.
Write down, on paper or use an editor, the step by step 'logic' you need and walk through that logic from beginning to end until the 'logic' works and produces the correct result.
You just now have started to do that when you listed those rules above.
But you left some things out. Expand on that list of 'rules' and provide a little more example data. TPD has given you a good example. Reread what they said.
Did you notice they start by talking about 'tasks': what each task does and the order the tasks need to be performed.
That 'task list' has NOTHING to do with Java, C, or any other language: it is identifying the problem/algorithm. Until you have that coding is premature.