Understanding problem statements is a crucial step in the low-level design process. It involves analyzing the requirements presented in the problem statement and identifying the key functionalities and data that the payment app needs to handle.

As a senior engineer with a background in Java development, you are already familiar with the importance of understanding problem statements in software development. Just like you analyze user stories and break them down into tasks in Agile development, the same principle applies here.

To effectively analyze problem statements, consider the following steps:

1. Read and Understand the Problem Statement: Start by carefully reading and comprehending the problem statement provided. Pay attention to the context, requirements, and any constraints mentioned.

2. Identify Key Functionalities: Identify the main functionalities that the payment app must provide. These functionalities can include features like user authentication, processing payments, generating invoices, and managing transactions.

3. Define User Roles and Permissions: Determine the different user roles and their specific permissions within the payment app. For example, you may have roles like customer, merchant, and admin, each with their own set of permissions.

4. Analyze Data Requirements: Identify the types of data that the payment app needs to handle. This can include customer information, product details, transaction history, and payment-related data.

5. Consider External Integrations: If the payment app needs to integrate with external systems or APIs, identify those integration points. For example, the app may need to integrate with a third-party payment gateway for processing transactions.

By thoroughly analyzing problem statements and identifying requirements, you lay the foundation for the subsequent steps in the low-level design process, such as creating a class diagram and defining entities and relationships.

Now, let's practice analyzing a problem statement related to our payment app. Consider the following problem statement:

"Design a payment app that allows customers to make payments for purchases and merchants to receive payments. Customers should be able to add items to a cart, view their cart, and proceed to payment. Merchants should be able to manage products, view transaction history, and withdraw funds from their account. Ensure that the app is secure and supports multiple payment methods."

Based on this problem statement, take a moment to analyze and identify the key functionalities and data requirements. How would you approach designing the payment app to fulfill the stated requirements? Take into consideration your Java development experience and think about how you would handle user authentication, managing transactions, and integrating payment methods. Feel free to write some notes or code snippets in the box below:

1// Replace this comment with your code or notes