Identifying Entities and Relationships
In low-level design, identifying entities and relationships is a critical step in understanding the structure and dependencies within a system. Entities are the objects or elements that exist within the system, while relationships define how these entities are interconnected.
In the context of designing a payment app, let's identify some entities and relationships:
Entities:
- User
- Transaction
- PaymentMethod
- Address
Relationships:
- A User can have multiple Transactions
- A Transaction is associated with a User
- A Transaction is associated with a PaymentMethod
- User has multiple Addresses
By identifying the entities and their relationships, we can begin to visualize how the different components of the payment app interact with each other.
Let's take a closer look at an example.
TEXT/X-JAVA
1// Example entity and relationship
2
3class User {
4
5 private int id;
6 private String name;
7 private String email;
8 private List<Address> addresses;
9 private List<Transaction> transactions;
10
11 // constructor, getters, and setters
12}
13
14class Transaction {
15
16 private int id;
17 private User user;
18 private PaymentMethod paymentMethod;
19 private double amount;
20 private boolean status;
21
22 // constructor, getters, and setters
23}
24
25class PaymentMethod {
26
27 private int id;
28 private String name;
29 private String type;
30 private boolean isActive;
31
32 // constructor, getters, and setters
33}
34
35class Address {
36
37 private int id;
38 private String street;
39 private String city;
40 private String state;
41 private String zipCode;
42
43 // constructor, getters, and setters
44}xxxxxxxxxxclass Main { public static void main(String[] args) { // Replace with your logic }}OUTPUT
:001 > Cmd/Ctrl-Enter to run, Cmd/Ctrl-/ to comment