Records (Java 14+)

Records are one of the most important modern features in Java. They were introduced as a preview in Java 14 and became a standard feature in Java 16.

Records provide a clean, concise, and efficient way to create immutable data classes. They are mainly used to store data without writing repetitive boilerplate code like getters, constructors, equals(), hashCode(), and toString().

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What are Records in Java?

A record is a special type of class designed to store immutable data. It provides a compact way to define data-carrying classes without writing repetitive code.

In simple words: A record is a short and clean way to create a class whose main purpose is to hold data.

Basic Syntax

record Person(String name, int age) {}

? That’s it! Java automatically generates everything for you.

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What Java Generates Automatically?

When you create a record, Java automatically generates all the essential methods and fields required for a data class. This removes the need to write repetitive boilerplate code.

• Private final fields (for all components)
• Constructor (to initialize values)
• Getter methods (accessor methods like name() and age())
• equals() method
• hashCode() method
• toString() method

Example

record Person(String name, int age) {}

public class Main {
    public static void main(String[] args) {
        Person p = new Person("Amit", 25);

        System.out.println(p.name());
        System.out.println(p.age());
    }
}

? You can access values using methods like name() and age() instead of traditional getters.

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Why Records Were Introduced?

Before records, creating a simple data class in Java required writing a lot of boilerplate code like constructors, getters, equals(), hashCode(), and toString(). This made the code lengthy and harder to maintain, especially in large applications where many such classes are needed.

class User {
    private final String name;
    private final int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() { return name; }
    public int getAge() { return age; }

    public boolean equals(Object o) { ... }
    public int hashCode() { ... }
    public String toString() { ... }
}

• Too much boilerplate code
• Hard to maintain and error-prone

With Records

record User(String name, int age) {}

? Java automatically handles all boilerplate code internally.

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Key Features of Records

Records in Java come with several built-in features that make them powerful and easy to use for creating data-carrying classes. They reduce boilerplate code and improve readability while keeping the structure clean and simple.

1. Immutable by Default

All fields in a record are final by default, meaning their values cannot be changed after object creation.

p.name = "Rahul";   //  Not allowed

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2. Less Boilerplate Code

Records remove the need to manually write common methods like constructors, getters, and utility methods.

? Instead of writing a long class, you can define everything in a single line.

record User(String name, int age) {}

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3. Auto-Generated Methods

Java automatically generates useful methods like getters, toString(), equals(), and hashCode().

User u = new User("Amit", 25);

System.out.println(u.name());      // getter
System.out.println(u.toString());  // string representation
System.out.println(u.equals(new User("Amit", 25))); // comparison

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4. Transparent Data Carrier

Records are mainly designed to carry data only, not to handle complex business logic.

? They are best used for simple data transfer between layers (like DTOs).

record Product(String name, double price) {}

Product p = new Product("Laptop", 55000);
System.out.println(p.name() + " - " + p.price());

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5. Custom Constructor (Compact Constructor)

You can also add validation logic using a compact constructor.

record Person(String name, int age) {
    public Person {
        if (age < 0) {
            throw new IllegalArgumentException("Age cannot be negative");
        }
    }
}

? This is useful for validating data during object creation.

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Adding Methods in Records

Records can also contain custom methods just like normal classes. These methods help you add behavior related to the data stored in the record.

record Person(String name, int age) {
    public String greeting() {
        return "Hello " + name;
    }
}

? This shows that even though records are mainly for data, you can still add useful methods when needed.

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Static Members in Records

Records can also contain static members, which belong to the class rather than the object.

record Test(int x) {
    static int count = 0;
}

? Static members are shared across all instances of the record.

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Real-World Use Cases

Records are mainly used in scenarios where you need to store and transfer data in a clean and efficient way. They are especially useful in modern Java applications like APIs and microservices.

• DTO (Data Transfer Objects) – Used to transfer data between layers
• API responses – Returning structured response data
• Configuration objects – Storing fixed settings or config values
• Database query results – Representing query output in a clean form
• Microservices data exchange – Passing data between services

Example

record Product(String name, double price) {}

public class Main {
    public static void main(String[] args) {
        Product p = new Product("Laptop", 50000);
        System.out.println(p);
    }
}

? Records are very useful when you just need a simple data container without complex logic.

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Advantages of Records

Records make Java code cleaner and more efficient, especially when working with simple data objects.

• Reduces boilerplate code – No need to write constructors, getters, or utility methods.
• Improves readability – Code becomes short and easy to understand.
• Immutable (thread-safe) – Data cannot be changed after creation, making it safer.
• Easy to maintain – Less code means fewer bugs and easier updates.
• Clean and modern design – Follows modern Java best practices.

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Limitations of Records

Although records are powerful, they have some restrictions because they are designed only for data storage.

• Cannot extend another class – Records implicitly extend java.lang.Record.
• Fields are always final – Values cannot be modified after creation.
• Not suitable for complex business logic – Designed only for simple data structures.
• Cannot define extra instance variables – Only declared components are allowed.

? Records are mainly data carriers, not full-featured business classes.

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Difference Between Records vs Normal Class

Feature	Record	Normal Class
Boilerplate	Very low (auto-generated code)	High (manual code required)
Mutability	Immutable by default	Can be mutable or immutable
Inheritance	Not allowed	Fully supported
Use Case	Data holder (DTOs, responses)	General-purpose logic classes

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When to Use Records?

Records should be used when your main requirement is to store and transfer data in a simple and clean way. They are best suited for lightweight data models where behavior is minimal.

• When you need simple data objects (like DTOs)
• When immutability is required for safety and consistency
• When you want clean, concise, and less verbose code

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When NOT to Use Records?

Records are not suitable in scenarios where you need more flexibility or complex behavior.

• When you have complex business logic
• When you need mutable objects (modifiable state)
• When you require inheritance or class extension

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Conclusion

Records in Java provide a modern and efficient way to create clean, concise, and immutable data classes. They remove the need for writing repetitive boilerplate code and make Java development more productive.

They are especially useful in modern applications where simplicity, clarity, and data-focused design are important.

• Helps write less and cleaner code
• Improves readability and structure
• Makes applications easier to maintain and scale

? Overall, records are an important feature for modern Java development, clean coding practices, and technical interviews.