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How to delimit new line when reading CSV file?

I am trying to read a file where each line has data members, separated by commas, that are meant to populate an object's data members, I tried using the regex "|" symbol to separate "," and "\n" along with "\r" for getting to the new line. However, after reading the first line, the first data member of the second line does not get read right away but rather a "" character gets read beforehand. Am I using the wrong regex symbols? or am I not using the right approach? I read that there are many ways to tackle this and opted to use scanner since seemed the most simple, using the buffer reader seemed very confusing since it seems like it returns arrays and not individual strings and ints which is I'm trying to get.
The CSV file looks something like this
stringA,stringB,stringC,1,2,3
stringD,stringE,stringF,4,5,6
stringG,stringH,stringI,7,8,9
My code looks something like this
//In list class
public void load() throws FileNotFoundException
{
Scanner input = new Scanner(new FileReader("a_file.csv"));
object to_add; //To be added to the list
input.useDelimiter(",|\\n|\\r");
while (input.hasNext())
{
String n = input.next(); //After the first loop run, this data gets the value ""
String l = input.next(); //During this second run, this member gets the data that n was supposed to get, "stringD"
String d = input.next(); //This one gets "stringE"
int a = input.nextInt(); //And this one tries to get "stringF", which makes it crash
int c = input.nextInt();
to_add = new object(n, l, d, a, b, c); //Calling copy constructor to populate data members
insert(to_add); //Inserting object to the list
}
input.close();
}

Use Apache Commons CSV. Here is the user guide https://commons.apache.org/proper/commons-csv/user-guide.html

You can do this with OpenCSV and here is a tutorial how to use this library. You can download the library from the Maven Repository.
So following is the code what you need to do,
Reader reader = Files.newBufferedReader(Paths.get("path/to/csvfile.csv"));
CSVReader csvReader = new CSVReader(reader);
List<String[]> dataList = new ArrayList<>();
dataList = csvReader.readAll();
reader.close();
csvReader.close();
Object to_add;
for (String[] rowData : dataList) {
String textOne = rowData[0];
String textTwo = rowData[1];
String textThree = rowData[2];
int numberOne = Integer.parseInt(rowData[3]);
int numberTwo = Integer.parseInt(rowData[4]);
int numberThree = Integer.parseInt(rowData[5]);
to_add = new Object(textOne, textTwo, textThree, numberOne, numberTwo, numberThree);
insert(to_add);
}

Having a bit of trouble reading in a file that contains specific information in each line

So I am having trouble reading in a file. The file contains 2 integers in the first line, and the rest of the file contains Strings in seperate lines. For some reason my logic in this code, it does not seem to consume each line in the file correctly. I tried to troubleshoot this by printing out what was happening, and it seems like the second nextLine() is not even executing.
while(inputFile.hasNext())
{
try
{
String start = inputFile.nextLine();
System.out.println(start); // tried to troubleshoot here
String [] rowsAndCols = start.split(" "); // part where it should read the first two integers
System.out.println(rowsAndCols[0]); // tried to troubleshoot here
int rows = Integer.parseInt(rowsAndCols[0]);
int cols = Integer.parseInt(rowsAndCols[1]);
cell = new MazeCell.CellType[rows+2][cols+2];
String mazeStart = inputFile.nextLine(); // part where it should begin to read the rest of the file containing strings
String [] mazeRowsAndCols = mazeStart.split(" ");
MazeCell.CellType cell2Add;

Based upon your description above, only the first line contains Integers, so your while loop is wrong as it is trying to convert every line into Integers.
Split into the code into
if (inputFile.hasNextLine())
{
String start = inputFile.nextLine();
String [] rowsAndCols = start.split(" "); // part where it should read the first two integers
int rows = Integer.parseInt(rowsAndCols[0]);
int cols = Integer.parseInt(rowsAndCols[1]);
}
then a while loop for the String reading

Read from .csv excel file and compute average

How do I read a .csv excel file with x number of rows and y number of columns, ignore irrelevant cells (things like names), then compute an average of the numbers in each column?
The Excel I have is something like this (, indicates new cell):
ID, week 1, week 2, week 3, .... , week 7
0 , 1 , 0.5 , 0 , , 1.2
1 , 0.5 , 1 , 0.5 , , 0.5
y , ......
so, how do I make it so it reads that kind of .csv file then computes an average in the format Week 1 = (Week 1 average), Week 2 = (week2 average) for all weeks?
Also am I correct in assuming I need to use a 2D Array for this?
Edit
Here's my code so far, it's very crude and I'm not sure if it does things properly yet:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class ClassAverage {
public static void main(String[] args){
readFile2Array("attendance.csv");
}
public static double[][] readFile2Array(String fileName){
try {
int rowCount = 0;
int colCount = 0;
Scanner rc = new Scanner(new File("attendance.csv"));
while (rc.hasNextLine()) {
rowCount++;
rc.nextLine();
}
rc.close();
System.out.println(rowCount);
Scanner cc = new Scanner(new File("attendance.csv"));
while (cc.hasNext()) {
colCount++;
cc.next();
}
cc.close();
colCount = colCount/rowCount;
System.out.println(colCount);
Scanner sc = new Scanner(new File("attendance.csv"));
double[][] spreadSheet = new double[rowCount][colCount];
while (sc.hasNext()) {
for (int i=0; i<spreadSheet.length; ++i){
for (int j=0; j<spreadSheet[i].length; ++j){
spreadSheet[i][j] = Double.parseDouble(sc.next());
}
}
}
sc.close();
return spreadSheet;
} catch (FileNotFoundException e) {
System.out.println("File cannot be opened");
e.printStackTrace();
}
return null;
}
public static double weeklyAvg(double[][] a){
}
}
So a summary of what it's intended to do
readFile2Array: read the csv file and count the number of rows, then count the total number of cells, divide total number of cells by number of rows to find number of columns. Read again and put each cell into the correct place in a 2D array.
weeklyAvg: I haven't thought up a way to do this yet, but it's supposed to read the array column by column and compute an average for each column, then print out the result.
PS. I'm very new at Java so I have no idea what some suggestions mean so I'd really appreciate suggestions that are pure java based without addons and stuff (I'm not sure if that's what some people are suggesting even). I hope it's not too much to ask for (if it's even possible).

You can use a Java library to handle your CSV file. For example opencsv ( you can find the latest maven version here http://mvnrepository.com/artifact/com.opencsv/opencsv/3.5)
And then you can parse your file like this :
CSVReader reader = new CSVReader(new FileReader("PATH_TO_YOUR_FILE"));
String[] nextLine;
int counter = 0;
while ((nextLine = reader.readNext()) != null) {
// nextLine[] is an array of values from the line
System.out.println(nextLine[0] + nextLine[1]);
}
You have to ignore the header line, you can simply do this by incrementing a counter and skipping the zero value.
To compute the average you can use a hashmap where the key is the column header name (example week 1). Then you increment with the current line value and after the loop is completed you divide by the number of lines (don't forget to substract the ignored lines like header line)

To parse simple CSV files, it's pretty simple to just manually parse through it, as long as you know the format is the same throughout the file and it does not contain errors
Create a storage data structure for each column you wish to compute (use a LinkedList<String>)
Read through the CSV file line by line with a BufferedReader
Use String.split(',') on each line and add the specific columns in the returned array to the correct LinkedList
Loop through the LinkedLists at the end and compute your averages (using Double.parseDouble() to convert the Strings to doubles)
To make sure that the String you're attempting to parse is a double, you can either use a try-catch statement or use a regex. Check Java: how to check that a string is parsable to a double? for more information

Scanning from a certain, random line of a file in java?

I have a .txt file that lists integers in groups like so:
20,15,10,1,2
7,8,9,22,23
11,12,13,9,14
and I want to read in one of those groups randomly and store the integers of that group into an array. How would I go about doing this? Every group has one line of five integers seperated by commas. The only way I could think of doing this is by incrementing a variable in a while loop that would give me the number of lines and then somehow read from one of those lines that is chosen randomly, but I'm not sure how it would read from only one of those lines randomly. Here's the code that I could come up with to sort of explain what I'm thinking:
int line = 0;
Scanner filescan = new Scanner (new File("Coords.txt"));
while (filescan.hasNextLine())
{
line++;
}
Random r = new Random(line);
Now what do I do to make it scan line r and place all of the integers read on line r into a 1-d array?

There is an old answer in StackOverflow about choosing a line randomly. By using the choose() method you can randomly get any line. I take no credit of the answer. If you like my answer upvote the original answer.
String[] numberLine = choose(new File("Coords.txt")).split(",");
int[] numbers = new int[5];
for(int i = 0; i < 5; i++)
numbers[i] = Integer.parseInt(numberLine[i]);

I'm assuming you know how to parse the line and get the integers out (Integer.parseInt, perhaps with a regular expression). If you're sing a scanner, you can specify that in your constructor.
Keep the contents of each line, and use that:
int line = 0;
Scanner filescan = new Scanner (new File("Coords.txt"));
List<String> content = new ArrayList<String>(); // new
while (filescan.hasNextLine())
{
content.add(filescan.next()); // new
line++;
}
Random r = new Random(line);
String numbers = content.get(r.nextInt(content.size()); // new
// Get numbers out of "numbers"

Read lines one by one from the file, store them in a list and generate a random number from the list's size and use it to get the random line.
public static void main(String[] args) throws Exception {
List<String> aList = new ArrayList<String>();
Scanner filescan = new Scanner(new File("Coords.txt"));
while (filescan.hasNextLine()) {
String nxtLn = filescan.nextLine();
//there can be empty lines in your file, ignore them
if (!nxtLn.isEmpty()) {
//add lines to the list
aList.add(nxtLn);
}
}
System.out.println();
Random r = new Random();
int randomIndex=r.nextInt(aList.size());
//get the random line
String line=aList.get(randomIndex);
//make 1 d array
//...
}

Merge sorting multiple files which have variable word counts

I am splitting a 10 GB file into multiple files of 100000 + few hundred words(since I read upto the line when I encounter 100000 words).
private void splitInputFile(String path) {
try{
File file=new File(path);
FileReader fr = new FileReader(file);
BufferedReader br = new BufferedReader(fr);
String temp;
temp = br.readLine();
String fileName="fileName";
int fileCount = 1;
while(temp!=null){
//TODO Read 100000 words, sort and write to a file. Repeat for the entire file
if(wordsToBeSorted.size()<=100000){
startCounting(temp);
temp=br.readLine();
}//end of if -> place 100000+ words inside the list
else{
Collections.sort(wordsToBeSorted);
fileName = "fileName"+fileCount;
fileCount++;
File splitFile = new File(fileName);
PrintWriter pr = new PrintWriter(splitFile);
for(String word:wordsToBeSorted){
pr.write(word);
pr.write("\n");//check if this works -> 1 word per line
}//end of for
}//end of else
}//end of while
mergeSort(fileCount);
}//end of try
catch(Exception e){
e.printStackTrace();
}
}
private void startCounting(String sb) {
StringTokenizer tokenizer = new StringTokenizer(sb);// Split by space
while (tokenizer.hasMoreTokens()) {
String text = tokenizer.nextToken();
text = text.replaceAll("\\W", "");// Remove all symbols
if("".equals(text.trim()))
continue;
wordsToBeSorted.add(text);
}
}
Now I wonder how to do a sorting with these files. I found out that I am supposed to do a Merge Sort. Considering the facts that each splitFile would have variable number of words(100000 + a few extra words), is it possible to do a merge sort involving files of variable word counts? Or should I follow some other approach to split the file?

is it possible to do a merge sort involving files of variable word counts?
Sure. I assume the goal here is external sorting. Just open up all input files (unless there are really really many, in which case you might have to do multiple runs), read the first word from each. Then identify the input with the smallest word, put that into the output and read the next word from that input. Close and remove any inputs which become empty, unless you have no more inputs.
If you have many inputs, you can use a heap to organize your inputs, with the next word as key. You'd remove the minimal object and then reinsert it after you have proceeded to the next word.