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How can I print 2 arrays with different values in java?

I am trying to print 2 different arrays, One array has the name of the file and the other array has the content of the csv file.
First I am reading the contents of the given file through the path and then putting the content of the .csv file into an array which is nextLine[]
public static void fileRead(File file) throws IOException, CsvException {
CSVReader csvReader = new CSVReaderBuilder(new FileReader(file)).withSkipLines(1).build();
String[] nextLine;
File folder = new File("src/main/resources/FolderDocumentsToRead");
String[] fileList = folder.list();
while((nextLine = csvReader.readNext())!=null){
System.out.println("Name of file: "+fileList[0]+", Title of Text: "+nextLine[0]);
}
}
}
The output I am trying to get is meant to look like;
Name of file: ATale.csv, Title of Text: A TALE OF THE RAGGED MOUNTAINS
Name of file: Diggling.csv, Title of Text: DIDDLING
The output I am getting looks like;
Name of file: ATale.csv, Title of Text: A TALE OF THE RAGGED MOUNTAINS
Name of file: ATale.csv, Title of Text: DIDDLING
I have tried using loops to get to the correct solution but I was just getting errors thrown at me and having a hard time with them.
I'm fairly new to using arrays and java in general, any tips would be appreciated even a tip towards getting the solution.
P.S first time using Stack overflow ahaha

Before the while loop, if you create a variable to keep track of the selected index then you will be able to modify it and have the change stay after the loop has finished.
int index = 0;
while(csvReader.hasNext())
{
String fileName = fileList[index];
String title = nextLine[index];
index++;
...
}

The line
while((nextLine = csvReader.readNext())!=null)
can be/should be rewritten like so:
while(csvReader.hasNext())
{
nextLine = csvReader.readNext();
...
}
This helps a lot with reading/debugging
NOTE this is not any sort of solution but a recommendation for ease-of-use

My CSV reader doesn't recognize missing value at the beginning and at the end of a row

Hi I'm working on a simple imitation of Panda's fillna method which requires me to replace a null/missing value in a csv file with an input (in terms of parameter). Almost everything is working fine but I have one issue. My CSV reader can't recognize the null/missing at the beginning and at the end of a row. For example,
Name,Age,Class
John,20,CLass-1
,18,Class-1
,21,Class-3
It will return errors.
Same goes to this example ..
Name,Age,Class
John,20,CLass-1
Mike,18,
Tyson,21,
But for this case (at the end of the row problem), I can solve this by adding another comma at the end. Like this
Name,Age,Class
John,20,CLass-1
Mike,18,,
Tyson,21,,
However, for the beginning of the row problem, I have no idea how to solve it.
Here's my code for the CSV file reader:
public void readCSV(String fileName) {
fileLocation = fileName;
File csvFile = new File(fileName);
Scanner sfile;
// noOfColumns = 0;
// noOfRows = 0;
data = new ArrayList<ArrayList>();
int colCounter = 0;
int rowCounter = 0;
try {
sfile = new Scanner(csvFile);
while (sfile.hasNextLine()) {
String aLine = sfile.nextLine();
Scanner sline = new Scanner(aLine);
sline.useDelimiter(",");
colCounter = 0;
while (sline.hasNext()) {
if (rowCounter == 0)
data.add(new ArrayList<String>());
data.get(colCounter).add(sline.next());
colCounter++;
}
rowCounter++;
sline.close();
}
// noOfColumns = colCounter;
// noOfRows = rowCounter;
sfile.close();
} catch (FileNotFoundException e) {
System.out.println("File to read " + csvFile + " not found!");
}
}

Unless you write a CSV file yourself, the writer mechanism will never arbitrarily add delimiters to suit the needs of your application method so, give up on that train of thought altogether because you shouldn't do it either. If you do indeed have access to the CSV file creation process then the simple solution would be to not allow the possibility of null or empty values to enter the file. In other words, have the defaults (in such a case) placed into empty elements as the CSV file is being written.
The Header line within a CSV file is there for a reason, it tells you the number of data columns and the names of those columns within each line (row) that make up the file. Between the header line and the actual data in the file you can also establish a pretty good idea of what each column Data Type should be.
In my opinion, the first thing your readCSV() method should do is read this Header Line (if it exists) and gather some information about the file that the method is about to iterate through. In your case the Header Line consists of:
Name,Age,Class
Right off the start we know that each line within the file consists of three (3) data columns. The first column contains the name of Name, the second column contains the name of Age, and the third column contains the name of Class. Based on all the information provided within the CSV file we can actually quickly assume the data types:
Name (String)
Age (Integer)
Class (String)
I'm only pointing this out because in my opinion, although not mandatory, I think it would be better to store the CSV data in an ArrayList or List Interface of an Object class, for example:
ArrayList<Student> studentData = new ArrayList<>();
// OR //
List<Student> studentData = new ArrayList<>();
where Student is an object class.
You seem to want everything within a 2D ArrayList so with that in mind, below is a method to read CSV files and place its' contents into this 2D ArrayList. Any file column elements that contain the word null or nothing at all will have a default string applied. There are lots of comments within the code explaining what is going on and I suggest you give them a read. This code can be easily modified to suit your needs. At the very least I hope it gives you an idea of what can be done to apply defaults to empty values within the CSV file:
/**
* Reads a supplied CSV file with any number of columnar rows and returns
* the data within a 2D ArrayList of String ({#code ArrayList<ArrayList<String>>}).
* <br><br>File delimited data that contains 'null' or nothing (a Null String (""))
* will have a supplied common default applied to that column element before it is
* stored within the 2D ArrayList.<br><br>
*
* Modify this code to suit your needs.<br>
*
* #param fileName (String) The CSV file to process.<br>
*
* #param csvDelimiterUsed (String) // The delimiter use in CSV file.<br>
*
* #param commonDefault (String) A default String value that can be common
* to all columnar elements within the CSV file that contains the string
* 'null' or nothing at all (a Null String ("")). Those empty elements will
* end up containing this supplied string value postfixed with the name of
* that column. As an Example, If the CSV file Header line was
* 'Name,Age,Class Room' and if the string "Unknown " is supplied to the
* commonDefault parameter and during file parsing a specific data column
* (let's say Age) contained the word 'null' or nothing at all (ex:
* Bob,null,Class-Math OR Bob,,Class-Math) then this line will be stored
* within the 2D ArrayList as:<pre>
*
* Bob, Unknown Age, Class-Math</pre>
*
* #return (2D ArrayList of String Type - {#code ArrayList<ArrayList<String>>})
*/
public ArrayList<ArrayList<String>> readCSV(final String fileName, final String csvDelimiterUsed,
final String commonDefault) {
String fileLocation = fileName; // The student data file name to process.
File csvFile = new File(fileLocation); // Create a File Object (use in Scanner reader).
/* The 2D ArrayList that will be returned containing all the CSV Row/Column data.
You should really consider creating a Class to hold Student instances of this
data however, this can be accomplish by working the ArrayList later on when it
is received. */
ArrayList<ArrayList<String>> fileData = new ArrayList<>();
// Open the supplied data file using Scanner (as per OP).
try (Scanner reader = new Scanner(csvFile)) {
/* Read the Header Line and gather information... This array
will ultimately be setup to hold default values should
any file columnar data hold null OR null-string (""). */
String[] columnData = reader.nextLine().split("\\s*\\" + csvDelimiterUsed + "\\s*");
/* How many columns of data will be expected per row.
This will be used in the String#split() method later
on as the limiter when we parse each file data line.
This limiter value is rather important in this case
since it ensures that a Null String ("") is in place
of where valid Array element should be should there
be no data available instead of just providing an
array of 'lesser length'. */
int csvValuesPerLineCount = columnData.length;
// Copy column Names Array: To just hold the column Names.
String[] columnName = new String[columnData.length];
System.arraycopy(columnData, 0, columnName, 0, columnData.length);
/* Create default data for columns based on the supplied
commonDefault String. Here the supplied default prefixes
the actual column name (see JavaDoc). */
for (int i = 0; i < columnData.length; i++) {
columnData[i] = commonDefault + columnData[i];
}
// An ArrayList to hold each row of columnar data.
ArrayList<String> rowData;
// Iterate through in each row of file data...
while (reader.hasNextLine()) {
rowData = new ArrayList<>(); // Initialize a new ArrayList.
// Read file line and trim off any leading or trailing white-spaces.
String aLine = reader.nextLine().trim();
// Only Process lines that contain something (blank lines are ignored).
if (!aLine.isEmpty()) {
/* Split the read in line based on the supplied CSV file
delimiter used and the number of columns established
from the Header line. We do this to determine is a
default value will be reguired for a specific column
that contains no value at all (null or Null String("")). */
String[] aLineParts = aLine.split("\\s*\\" + csvDelimiterUsed + "\\s*", csvValuesPerLineCount);
/* Here we determine if default values will be required
and apply them. We then add the columnar row data to
the rowData ArrayList. */
for (int i = 0; i < aLineParts.length; i++) {
rowData.add((aLineParts[i].isEmpty() || aLineParts[i].equalsIgnoreCase("null"))
? columnData[i] : aLineParts[i]);
}
/* Add the rowData ArrayList to the fileData
ArrayList since we are now done with this
file row of data and will now iterate to
the next file line for processing. */
fileData.add(rowData);
}
}
}
// Process the 'File Not Found Exception'.
catch (FileNotFoundException ex) {
System.err.println("The CSV file to read (" + csvFile + ") can not be found!");
}
// Return the fileData ArrayList to the caller.
return fileData;
}
And to use the method above you might do this:
ArrayList<ArrayList<String>> list = readCSV("MyStudentsData.txt", ",", "Unknown ");
if (list == null) { return; }
StringBuilder sb;
for (int i = 0; i < list.size(); i++) {
sb = new StringBuilder("");
for (int j = 0; j < list.get(i).size(); j++) {
if (!sb.toString().isEmpty()) { sb.append(", "); }
sb.append(list.get(i).get(j));
}
System.out.println(sb.toString());
}

Reading a CSV file into a 2d Array

I've been trying for days to learn how to create this code. It's a homework example. Beginner Java Final Project. I'm about to rip out my hair, if you could guide me a little, I'd appreciate it. I can't seem to figure out how to parse the csv file into a proper 2d array. The delimiter is a ",". I need to maniuplate one column of data (such as the year), but ignore the first (0,0), (0,1), (0,2) row as it only carries the labels I believe. I'm so lost. What I have prints out the first column, but how would I ignore the label at (0,0), and how would I store this information so I could manipulate it in a method? I don't need help on most of the assignment except how to read the values properly and then be able to manipulate them. Thank you.
import java.util.*;
import java.io.*;
public class BasicFileIO{
public static void main (String[] args) {
String fileName = "Crime.csv";
File file = new File(fileName);
try {
Scanner input = new Scanner(file);
while (input.hasNext()) {
String data = input.nextLine();
String[] values = data.split(",");
System.out.println(values[0]);
}
}catch (Exception e) {
System.out.printf("Error");
}
}
}
HERE IS AN IMAGE OF THE CSV FILE. I couldn't upload it. This is how it looks in google docs, but if I open it in atom it's just a file with commas and values (not in cells).
CSV screenshot

You can read and parse scv files with apache commons-csv. Here's an example for reading the columns with this library:
Reader in = new FileReader("path/to/file.csv");
Iterable<CSVRecord> records = CSVFormat.EXCEL.parse(in);
for (CSVRecord record : records) {
String lastName = record.get("Last Name"); // or you can pass the index of column
String firstName = record.get("First Name");
}

Csv: search for String and replace with another string

I have a .csv file that contains:
scenario, custom, master_data
1, ${CUSTOM}, A_1
I have a string:
a, b, c
and I want to replace 'custom' with 'a, b, c'. How can I do that and save to the existing .csv file?

Probably the easiest way is to read in one file and output to another file as you go, modifying it on a per-line basis
You could try something with tokenizers, this may not be completely correct for your output/input, but you can adapt it to your CSV file formatting
BufferedReader reader = new BufferedReader(new FileReader("input.csv"));
BufferedWriter writer = new BufferedWriter(new FileWriter("output.csv"));
String custom = "custom";
String replace = "a, b, c";
for(String line = reader.readLine(); line != null; line = reader.readLine())
{
String output = "";
StringTokenizer tokenizer = new StringTokenizer(line, ",");
for(String token = tokenizer.nextToken(); tokenizer.hasMoreTokens(); token = tokenizer.nextToken())
if(token.equals(custom)
output = "," + replace;
else
output = "," + token;
}
readInventory.close();
If this is for a one off thing, it also has the benefit of not having to research regular expressions (which are quite powerful and useful, good to know, but maybe for a later date?)

Have a look at Can you recommend a Java library for reading (and possibly writing) CSV files?
And once the values have been read, search for strings / value that start with ${ and end with }. Use Java Regular Expressions like \$\{(\w)\}. Then use some map for looking up the found key, and the related value. Java Properties would be a good candidate.
Then write a new csv file.

Since your replacement string is quite unique you can do it quickly without complicated parsing by just reading your file into a buffer, and then converting that buffer into a string. Replace all occurrences of the text you wish to replace with your target text. Then convert the string to a buffer and write that back to the file...
Pattern.quote is required because your string is a regular expression. If you don't quote it you may run into unexpected results.
Also it's generally not smart to overwrite your source file. Best is to create a new file then delete the old and rename the new to the old. Any error halfway will then not delete all your data.
final Path yourPath = Paths.get("Your path");
byte[] buff = Files.readAllBytes(yourPath);
String s = new String(buff, Charset.defaultCharset());
s = s.replaceAll(Pattern.quote("${CUSTOM}"), "a, b, c");
Files.write(yourPath, s.getBytes());

Java: CSV File Easy Read/Write

I'm working on a program that requires quick access to a CSV comma-delimited spreadsheet file.
So far I've been able to read from it easily using a BufferedReader.
However, now I want to be able to edit the data it reads, then export it BACK to the CSV.
The spreadsheet contains names, phone numbers, email addresses, etc. And the program lists everyone's data, and when you click on them it brings up a page with more detailed information, also pulled from the CSV. On that page you can edit the data, and I want to be able to click a "Save Changes" button, then export the data back to its appropriate line in the CSV--or delete the old one, and append the new.
I'm not very familiar with using a BufferedWriter, or whatever it is I should be using.
What I started to do is create a custom class called FileIO. It contains both a BufferedReader and a BufferedWriter. So far it has a method that returns bufferedReader.readLine(), called read(). Now I want a function called write(String line).
public static class FileIO {
BufferedReader read;
BufferedWriter write;
public FileIO (String file) throws MalformedURLException, IOException {
read = new BufferedReader(new InputStreamReader (getUrl(file).openStream()));
write = new BufferedWriter (new FileWriter (file));
}
public static URL getUrl (String file) throws IOException {
return //new URL (fileServer + file).openStream()));
FileIO.class.getResource(file);
}
public String read () throws IOException {
return read.readLine();
}
public void write (String line) {
String [] data = line.split("\\|");
String firstName = data[0];
// int lineNum = findLineThatStartsWith(firstName);
// write.writeLine(lineNum, line);
}
};
I'm hoping somebody has an idea as to how I can do this?

Rather than reinventing the wheel you could have a look at OpenCSV which supports reading and writing of CSV files. Here are examples of reading & writing

Please consider Apache commons csv.
To fast understand the api, there are four important classes:
CSVFormat
Specifies the format of a CSV file and parses input.
CSVParser
Parses CSV files according to the specified format.
CSVPrinter
Prints values in a CSV format.
CSVRecord
A CSV record parsed from a CSV file.
Code Example:
Unit test code:

The spreadsheet contains names, phone numbers, email addresses, etc. And the program lists everyone's data, and when you click on them it brings up a page with more detailed information, also pulled from the CSV. On that page you can edit the data, and I want to be able to click a "Save Changes" button, then export the data back to its appropriate line in the CSV--or delete the old one, and append the new.
The content of a file is a sequence of bytes. CSV is a text based file format, i.e. the sequence of byte is interpreted as a sequence of characters, where newlines are delimited by special newline characters.
Consequently, if the length of a line increases, the characters of all following lines need to be moved to make room for the new characters. Likewise, to delete a line you must move the later characters to fill the gap. That is, you can not update a line in a csv (at least not when changing its length) without rewriting all following lines in the file. For simplicity, I'd rewrite the entire file.
Since you already have code to write and read the CSV file, adapting it should be straightforward. But before you do that, it might be worth asking yourself if you're using the right tool for the job. If the goal is to keep a list of records, and edit individual records in a form, programs such as Microsoft Access or whatever the Open Office equivalent is called might be a more natural fit. If you UI needs go beyond what these programs provide, using a relational database to keep your data is probably a better fit (more efficient and flexible than a CSV).

Add Dependencies
implementation 'com.opencsv:opencsv:4.6'
Add Below Code in onCreate()
InputStreamReader is = null;
try {
String path= "storage/emulated/0/Android/media/in.bioenabletech.imageProcessing/MLkit/countries_image_crop.csv";
CSVReader reader = new CSVReader(new FileReader(path));
String[] nextLine;
int lineNumber = 0;
while ((nextLine = reader.readNext()) != null) {
lineNumber++;
//print CSV file according to your column 1 means first column, 2 means
second column
Log.e(TAG, "onCreate: "+nextLine[2] );
}
}
catch (Exception e)
{
Log.e(TAG, "onCreate: "+e );
}

I solved it using
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-csv</artifactId>
<version>2.8.6</version>
</dependency>
and
private static final CsvMapper mapper = new CsvMapper();
public static <T> List<T> readCsvFile(MultipartFile file, Class<T> clazz) throws IOException {
InputStream inputStream = file.getInputStream();
CsvSchema schema = mapper.schemaFor(clazz).withHeader().withColumnReordering(true);
ObjectReader reader = mapper.readerFor(clazz).with(schema);
return reader.<T>readValues(inputStream).readAll();
}