The provided code defines a private method named `mappingTransaction` that...

The provided code defines a private method named mappingTransaction that processes a list of transactions (transactions) and maps them into a new list of AccountTransaction objects based on various constraints and business logic. Here's a detailed breakdown of what the code does:

Inputs to the Function:

• transactions: A list of TransactionListDetails objects, each representing a banking transaction.
• transTextCodeMap: A map containing transaction text codes and associated values.
• accountNumber: The account number associated with the transactions.
• mainCategory and subCategory: Strings representing categories of the transactions (e.g., "fees", "unknowntrans").
• caseId: A unique identifier for a particular case.

Outputs of the Function:

• Returns a list of AccountTransaction objects (accountTransactions), which are processed and filtered based on predefined rules.

What the Code Does:

1. Initialization:

   • Creates a new list to hold AccountTransaction instances (accountTransactions).
   • Checks if the transactions list is non-null and contains elements. If not, an empty list is returned immediately.

2. Fetch Additional Data:

   • Retrieves a fetchFromDate, which represents the date from which disputed transactions are fetched.
   • Retrieves a list of disputed transactions (transArsInfos) from an external service (arsDailyBankTransService) using the account number and date.

3. Iterate Through Transactions:

   • Loops through each TransactionListDetails object in the transactions list.
   • For each transaction:
     • Validates certain conditions:
       • Checks whether transTextCodeMap is null or verifies the presence of a valid textCode in the map and that the bookedDate is not null.
       • Filters out certain transactions based on mainCategory, subCategory, and the transaction's amount (e.g., negative or null amounts are skipped for specific categories).
     • Creates a new AccountTransaction object (bankTransaction) for valid records:
       • Maps properties of TransactionListDetails (e.g., amount, textCode, description) to AccountTransaction.
       • Concatenates transaction text lines (textLine1, textLine2, textLine3) to derive the merchant's name.
       • Attempts to format and set dates (transDate, usageDate) and amounts with specific formats. Logs any exceptions that occur during formatting.
     • Updates AccountTransaction to mark whether it has an already-raised complaint:
       • Compares date, amount, and description fields with the disputed transactions fetched from arsDailyBankTransService.
       • If a match is found and the caseId is different, sets complaintRaised to true.

4. Add to Resultant List:

   • Adds the bankTransaction object to the accountTransactions list if it satisfies all conditions.
   • Increments the reference number ("i") used for transRef.

5. Return:

   • The method returns the processed accountTransactions list.

Business Logic Summary:

• Maps transactions (TransactionListDetails) to formatted account transaction objects (AccountTransaction).
• Filters, validates, and skips transactions based on categories (mainCategory, subCategory) and conditions like negative amounts or null fields.
• Flags transactions for which complaints are already raised based on a comparison with disputed transactions.
• Formats transaction dates and amounts, handling any exceptions during formatting.

Example Use Case:

This method can be used in a financial service application to process raw transaction data for an account, transform it into a structured format, and flag transactions that have existing complaints or disputes. The output list would then be used for further customer-facing rendering, analysis, or reporting.