In software development, low level design refers to the process of translating the high level design and architectural decisions into a detailed design that can be implemented. It focuses on the internal structure of the system, including the organization of modules, the relationships between them, and the algorithms and data structures used.

As a senior engineer with a strong background in Java development, Spring Boot, MySQL, and AWS, understanding low level design is crucial for efficiently building robust and scalable applications. Just like a solid foundation is essential for constructing a building, low level design provides the foundation for the successful implementation of software systems.

To understand the importance of low level design, let's consider an analogy with building a house. The architectural design of the house provides the overall layout and structure, similar to the high level design in software development. However, the low level design involves detailed decisions such as the specific materials to use for constructing the walls, the plumbing and electrical systems, and the interior design.

Similarly, in software development, low level design addresses the specifics of how the different components of a system will interact and function. It defines the modules, classes, methods, and variables required to implement the desired functionality.

Let's dive into an example to illustrate the concept of low level design. Imagine you are tasked with designing a payment app. You have already identified the high level requirements, such as the ability to process payments, generate invoices, and manage user accounts. Now, it's time to break down these requirements into a detailed design.

One aspect of the low level design for the payment app is the class diagram. This diagram depicts the classes and their relationships in the system. Just like architectural blueprints of a house, the class diagram provides a visual representation of how the different classes interact and collaborate to achieve the desired functionality. It helps ensure that the code is organized, maintainable, and extensible.

Let's take a look at a simplified class diagram for the payment app:

1class Payment {
2    private Account account;
3    private BigDecimal amount;
4
5    public Payment(Account account, BigDecimal amount) {
6        this.account = account;
7        this.amount = amount;
8    }
9
10    public void processPayment() {
11        // Logic to process the payment
12    }
13}
14
15class Account {
16    private String accountNumber;
17    private BigDecimal balance;
18
19    // Getters and setters
20}

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class Main {

  public static void main(String[] args) {

    // Replace with your Java logic here

    Payment payment = new Payment(new Account("1234567890"), new BigDecimal("100.00"));

    payment.processPayment();

  }

}