Find null values in a CSV File using Java

To  find null values in a CSV file using Java,you can use the ‘openCSV’ library,which provides an easy-to-use API for reading and writing CSV files.Below,i will provide a step-by-step process.

Steps to Find Null Values in a CSV File

 

1.Add the OpenCSV Dependency:  If you are using Maven,add the OpenCSV dependency to your ‘pom.xml’.

2.Read the  CSV File:Use OpenCSV to read the CSV file.

3.Check for Null Values:Iterate through the records and check for null or empty values.

4.Output the Results:Print out the rows and columns where null values are found.

 

Maven Dependency

Add the following dependency to your ‘pom.xml’ file if you are using Maven:

<dependency>
    <groupId>com.opencsv</groupId>
    <artifactId>opencsv</artifactId>
    <version>5.5.2</version>
</dependency>

Java Code Example

Here is a complete Java program that reads a CSV file and finds null or empty values:

 
import com.opencsv.CSVReader;
import com.opencsv.exceptions.CsvException;

import java.io.FileReader;
import java.io.IOException;
import java.util.List;


public class FindNullValuesInCSV{

     public static void main(String[] args) {
           String csvFile="data.csv";

           try (CSVReader reader = new CSVReader(new FileReader(csvFile))) {
                List<String[]> records = reader.readAll();
                 for (int row = 0;row < records.size(); row++) 
                      String[] record = records.get(row);
                      for (int col = 0; col < record.length; col++) {
                           if (record[col]== null || record[col].trim().isEmpty()) {
                               System.out.println("Null or empty value found at row " + (row + 1) + ", column " + (col + 1));
                           }
                      }
                 }
           } catch(IOException | CsvException e) {
               e.printStackTrace();
           }
       }
}

Explanation

1. Import Statements:Import the necessary classes from OpenCSV and Java I/O.

2.File Path:Define the path to your CSV file.

3.CSVReader:Create a ‘CSVReader’ object to read the CSV file.

4.Read All Records:Use the ‘readAll()’ method to read all records into a list.

5.iterate Through Records:Loop through each record(row) and each field (column) to check for null or empty values.

6.Output:Print the row and column indices where null or empty values are found.

 

CSV File Example(‘data.csv’)

Here  is an example of what the ‘data.csv’ file might look like:

Name,Age,Location
Surya,30,Pakisthan
Dev, ,India
Raj,25,
,22,Sri Lanka
Eshwar,35,Bangladesh

 

Expected Output

When you run the Java program with the above CSV file,the output will be:

Null or empty value found at row 2,column 2
Null or empty value found at row 3,column 3
Null or empty value found at row 4,column 1

Main Idea

• Add Dependency:Add the OpenCSV dependency to your project.
• Read CSV:Use ‘csvReader’ to read the CSV file.
• Check for Nulls:Iterate through the records and check for null or empty values.
• Print Results:Output the positions of the null or empty values.

This approach provides a straightforward method to find null values in a CSV file using Java and OpenCSV.