Using Java 8 Stream API for Entity to DTO Conversion (With Java Record)

Java 8 introduced the Stream API, which provides a functional approach to processing collections. One of the common real-world scenarios in software development is converting an Entity (Customer) to a DTO (Data Transfer Object).

In this guide, we will compare the traditional approach (pre-Java 8) with the Stream API approach for converting Customer entities into CustomerDTOs.

Java records were introduced in Java 14 and became a standard feature in Java 16. They provide a concise way to create immutable data carriers without needing boilerplate code like constructors, getters, setters, and toString() methods.

1️⃣ Why Use Java Records for DTOs?

✔ Immutable — Once created, the data cannot be modified.
✔ Concise — No need for getters, setters, or constructor definitions.
✔ Auto-Generated Methods — equals(), hashCode(), and toString() are provided automatically.
✔ Thread-Safe – Because of immutability, records are inherently thread-safe.

2️⃣ Customer Entity and CustomerDTO as a Java Record

Before implementing the conversion logic, let’s define our Customer entity and use a Java record for DTO.

📌 Customer Entity (Standard Java Class)

public class Customer {…