Question

Implement a class CSVReader that reads a CSV file, and provide methods:

int numbOfRows()

int numberOfFields(int row)

String field(int row, int column)

Please use the CSVReader and CSVReaderTester class to complete the code. I have my own CSV files and cannot copy them to here. So if possible, just use a random CSV file.

CSVReader.java

import java.util.ArrayList;
import java.util.Scanner;
import java.io.*;

/**
   Class to read and process the contents of a standard CSV file
*/
public class CSVReader
{
   ...
  
   /**
Constructor opens the input file and stores each line in
a list of Strings.
@param fileName the name of the csv file to be processed
   */
   public CSVReader(String fileName)
   {
...
   }
  
   /**
Returns the number of lines in the CSV file
@return the number of rows (lines) in the file
   */
   public int numberOfRows()
   {
...
   }
  
   /**
Returns the number of fields in a particular row
@param row the line number (0 <= row < number of lines)
@return the number of fields in the given row
   */
   public int numberOfFields(int row)
   {
...
   }
  
   /**
Returns the field in a particular row and colum
@param row the line number (0 <= row < number of lines)
@param column the column number (0 <= row < number of columns in row)
@return the number of fields in the given row
   */
   public String field(int row, int column)
   {
...
   }
}

CSVReaderTester.java

/**
   This program demonstrates and tests methods of the CSVReader class.
*/
public class CSVReaderTester
{
   public static void main(String[] args)
   {
CSVReader reader1 = new CSVReader("att2007.csv");
CSVReader reader2 = new CSVReader("quotes.csv");
  
System.out.println("Number of rows: " + reader1.numberOfRows());
System.out.println("Expected: 214");
System.out.println("Number of fields in row 10: " + reader1.numberOfFields(10));
System.out.println("Expected: 7");
System.out.println("Row 10, Col 2: " + reader1.field(10, 2));
System.out.println("Expected: 24.95");

System.out.println("Number of rows: " + reader2.numberOfRows());
System.out.println("Expected: 2");
System.out.println("Number of fields in row 1: " + reader2.numberOfFields(1));
System.out.println("Expected: 4");
System.out.println("Row 1, Col 2: " + reader2.field(1, 2));
System.out.println("Expected: Hello, World");
System.out.println("Row 1, Col 3: " + reader2.field(1, 3));
System.out.println("Expected: He asked: \"Quo vadis?\"");
System.out.println("Row 0, Col 3: " + reader2.field(0, 3));
System.out.println("Expected: \"..., that all men are created equal, ...\"");
   }
}

Answer 1

Just change the file path mentioned in the code before running it

import java.util.ArrayList;
import java.util.Scanner;
import java.io.*;

/**
 Class to read and process the contents of a standard CSV file
 */


public class CSVReaderTester
{
    public static void main(String[] args)
    {
        CSVReader reader1 = new CSVReader("/Users/sample/Desktop/csv.csv");
        CSVReader reader2 = new CSVReader("/Users/sample/quotes.csv");

        System.out.println("Number of rows: " + reader1.numberOfRows());
        System.out.println("Expected: 214");
        System.out.println("Number of fields in row 10: " + reader1.numberOfFields(10));
        System.out.println("Expected: 7");
        System.out.println("Row 10, Col 2: " + reader1.field(10, 2));
        System.out.println("Expected: 24.95");

        System.out.println("Number of rows: " + reader2.numberOfRows());
        System.out.println("Expected: 2");
        System.out.println("Number of fields in row 1: " + reader2.numberOfFields(1));
        System.out.println("Expected: 4");
        System.out.println("Row 1, Col 2: " + reader2.field(1, 2));
        System.out.println("Expected: Hello, World");
        System.out.println("Row 1, Col 3: " + reader2.field(1, 3));
        System.out.println("Expected: He asked: \"Quo vadis?\"");
        System.out.println("Row 0, Col 3: " + reader2.field(0, 3));
        System.out.println("Expected: \"..., that all men are created equal, ...\"");
    }
}


class CSVReader
{
    static ArrayList<String > rows = new ArrayList<>();


    /**
     Constructor opens the input file and stores each line in
     a list of Strings.
     @param fileName the name of the csv file to be processed
     */
    public CSVReader(String fileName)
    {
        String line = "";

        int i=0;
        try (BufferedReader br = new BufferedReader(new FileReader(fileName))) {

            while ((line = br.readLine()) != null) {
                rows.add(i, line);

                i++;

            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     Returns the number of lines in the CSV file
     @return the number of rows (lines) in the file
     */
    public int numberOfRows()
    {
        return rows.size();
    }

    /**
     Returns the number of fields in a particular row
     @param row the line number (0 <= row < number of lines)
     @return the number of fields in the given row
     */
    public int numberOfFields(int row)
    {

        String[] fields = rows.get(row-1).split(",");
        return fields.length;
    }

    /**
     Returns the field in a particular row and colum
     @param row the line number (0 <= row < number of lines)
     @param column the column number (0 <= row < number of columns in row)
     @return the number of fields in the given row
     */
    public String field(int row, int column)
    {
        String[] fields = rows.get(row-1).split(",");
        return fields[column-1];
    }
}


/**
 This program demonstrates and tests methods of the CSVReader class.
 */