The attached project is created using Java on Eclipse IDE.

Please run 'ExtractCustomerInvoice.java' to see the extracted information in 3 different CSV files.

The respective CSV file (sales.csv) was found on the Kaggle.com and was preprocessed to match the needs of the project. The other supporting files are as listed below:

1. customer_sample1.csv

   Selected list of customers. I have only 50 customers in this CSV ( problem statement mentions 1000).

2. customer1.csv

   List of all the customers invloved in the business scenario with their Firstname and Lastname (as per the problem statement.)

3. invoice1.csv

   List of all the customer invoice generated as part of the business scenario (as per the problem statement.)

4. invoice_item1.csv

   list of all the invoice items generated in the business domain (as per the problem statement.)

The sales data has around 2800 records and the code will extract customer and invoice data for 50 selected customers (out of 92).Code will work for 1000 selected customers input through the 'customers_sample1.csv' file.

The successful execution of the project will create 3 CSV files:

1. extracted_customer.csv
2. extracted_invoice.csv
3. extracted_invoice_item.csv

The code is simple and easy to understand with comments.