How to handle files in Java for QA Engineers

As a QA Engineer, especially when dealing with automation using Java, it's essential to understand how file handling works. Whether it’s reading a test data file, logging test results, or writing reports — **basic file operations** are a part of real-time QA work.

In this blog post, you will learn:
- How to create, write, read, and delete a file in Java
- How to read/write Excel files using Apache POI
- Real-world QA scenarios where file handling is useful
- Some practice questions to boost your understanding

📂 1. Creating a File in Java

You can create a new file using the File class.

import java.io.File;

public class CreateFile {
  public static void main(String[] args) {
    try {
      File file = new File("testdata.txt");
      if (file.createNewFile()) {
        System.out.println("File created: " + file.getName());
      } else {
        System.out.println("File already exists.");
      }
    } catch (Exception e) {
      System.out.println("Error: " + e.getMessage());
    }
  }
}

📝 2. Writing to a File

Use FileWriter to write content to a file. This is very useful when you want to log automation results or export some data.

import java.io.FileWriter;

public class WriteToFile {
  public static void main(String[] args) {
    try {
      FileWriter writer = new FileWriter("testdata.txt");
      writer.write("This is written by QA automation.");
      writer.close();
      System.out.println("Successfully wrote to file.");
    } catch (Exception e) {
      System.out.println("Error: " + e.getMessage());
    }
  }
}

📖 3. Reading from a File

Use FileReader along with BufferedReader to read text files. Common use case: reading test data or config values.

import java.io.BufferedReader;
import java.io.FileReader;

public class ReadFromFile {
  public static void main(String[] args) {
    try {
      BufferedReader br = new BufferedReader(new FileReader("testdata.txt"));
      String line;
      while ((line = br.readLine()) != null) {
        System.out.println(line);
      }
      br.close();
    } catch (Exception e) {
      System.out.println("Error: " + e.getMessage());
    }
  }
}

🗑️ 4. Deleting a File

Sometimes you may want to delete old logs or temp files at the end of test execution. Use File.delete().

import java.io.File;

public class DeleteFile {
  public static void main(String[] args) {
    File file = new File("testdata.txt");
    if (file.delete()) {
      System.out.println("Deleted file: " + file.getName());
    } else {
      System.out.println("Failed to delete file.");
    }
  }
}

📊 5. Reading and Writing Excel Files (Apache POI)

Most test cases use Excel for input data. You can read/write Excel files using Apache POI library.

📦 Required JARs:

• poi-xxx.jar
• poi-ooxml-xxx.jar
• poi-ooxml-schemas-xxx.jar
• xmlbeans-xxx.jar

You can download these from: https://poi.apache.org/download.html

✅ Read Excel File

import java.io.File;
import java.io.FileInputStream;
import org.apache.poi.xssf.usermodel.*;

public class ReadExcel {
  public static void main(String[] args) throws Exception {
    FileInputStream fis = new FileInputStream(new File("data.xlsx"));
    XSSFWorkbook workbook = new XSSFWorkbook(fis);
    XSSFSheet sheet = workbook.getSheet("Sheet1");
    String value = sheet.getRow(0).getCell(0).getStringCellValue();
    System.out.println("Cell Value: " + value);
    workbook.close();
  }
}

✅ Write to Excel File

import java.io.FileOutputStream;
import org.apache.poi.xssf.usermodel.*;

public class WriteExcel {
  public static void main(String[] args) throws Exception {
    XSSFWorkbook workbook = new XSSFWorkbook();
    XSSFSheet sheet = workbook.createSheet("Sheet1");
    sheet.createRow(0).createCell(0).setCellValue("QA Rocks!");
    FileOutputStream fos = new FileOutputStream("data.xlsx");
    workbook.write(fos);
    workbook.close();
    fos.close();
  }
}

💡 Real-Time QA Use Cases

• Read data from Excel sheet for test inputs
• Write test results to Excel for client reporting
• Delete old logs before fresh test execution
• Read .txt or config files for environment setup

🧪 Practice Questions

• Write a program to read a file and count how many words it has
• Write a program to append logs to a file after each test case
• Create a file with dynamic name based on date/time
• Write test data to Excel from an ArrayList
• Read a 2D Excel sheet and print all rows and columns
• Delete all ".log" files from a directory using Java

🔚 Conclusion

Whether you're working on Selenium, API, or Backend testing — understanding file handling in Java gives you an extra edge as a QA engineer. It makes your automation flexible and powerful. Master the basics, practice regularly, and slowly integrate file handling into your real-world test scripts.

If you liked this post, don’t forget to share it with your QA community and drop a comment with your feedback or doubts!