Remove Boilerplate Code in Kotlin, Python, Java, and C#


Kotlin data class, Python @dataclass, Java record, and C# record

Boilerplate code is one of the quiet productivity killers in software engineering. It bloats codebases, obscures intent, increases maintenance cost, and—ironically—introduces bugs in code that “should have been trivial.”

Modern programming languages have converged on a powerful idea: data-centric types should be concise, immutable by default, and behaviorally predictable. Kotlin, Python, Java, and C# all provide first-class constructs to achieve this.

This article explains how to avoid boilerplate code using:

  • Kotlin data class
  • Python @dataclass
  • Java record
  • C# record

We’ll use production-style examples, not toy snippets.


The Problem: Boilerplate in Data Models

Traditional object-oriented data models typically require you to manually implement:

  • Constructors
  • Getters / setters
  • equals / hashCode
  • toString
  • Copy or cloning logic

Example (classic Java POJO):

public class User {
    private final String id;
    private final String email;
    private final boolean active;

    public User(String id, String email, boolean active) {
        this.id = id;
        this.email = email;
        this.active = active;
    }

    public String getId() { return id; }
    public String getEmail() { return email; }
    public boolean isActive() { return active; }

    // equals, hashCode, toString...
}

This is structural noise. The signal—what the data actually is—is buried.


Kotlin: data class for Expressive Domain Models

Kotlin’s data class is designed for value semantics. The compiler generates:

  • equals() / hashCode()
  • toString()
  • copy()
  • Component functions (for destructuring)

Production Example: Order Snapshot

data class OrderSnapshot(
    val orderId: String,
    val customerId: String,
    val totalAmount: BigDecimal,
    val currency: Currency,
    val createdAt: Instant
)

Why This Matters in Production

val original = OrderSnapshot(
    orderId = "ORD-1001",
    customerId = "C-42",
    totalAmount = BigDecimal("149.99"),
    currency = Currency.getInstance("USD"),
    createdAt = Instant.now()
)

val refunded = original.copy(totalAmount = BigDecimal.ZERO)

✔ Immutable by default
✔ Safe copying without mutation
✔ Excellent logging and debugging via toString()
✔ Ideal for DTOs, events, API contracts, and aggregates

Best Practice:
Use data class only for pure data. Avoid embedding heavy business logic.


Python: @dataclass for Clean, Explicit Models

Python’s @dataclass decorator removes boilerplate while preserving flexibility. You get:

  • Auto-generated __init__
  • __repr__
  • __eq__
  • Optional immutability

Production Example: API Payload Model

from dataclasses import dataclass
from datetime import datetime
from typing import Optional

@dataclass(frozen=True)
class PaymentRequest:
    transaction_id: str
    amount: float
    currency: str
    requested_at: datetime
    description: Optional[str] = None

Usage in Real Systems

request = PaymentRequest(
    transaction_id="TXN-9912",
    amount=49.99,
    currency="EUR",
    requested_at=datetime.utcnow()
)

✔ Explicit and readable
✔ Type-hint friendly (works with mypy, pydantic, FastAPI)
frozen=True enables safe immutability
✔ Excellent for microservices and message schemas

Best Practice:
Use @dataclass for data transport and configuration, not as an Active Record replacement.


Java: record for Immutable Value Objects

Java records (Java 16+) finally give Java a first-class value type.

A record automatically provides:

  • Canonical constructor
  • Accessors
  • equals, hashCode, toString

Production Example: Audit Log Entry

import java.time.Instant;

public record AuditEvent(
    String eventId,
    String actor,
    String action,
    Instant timestamp
) {}

Why Records Are a Big Deal

AuditEvent event = new AuditEvent(
    "EVT-7",
    "system",
    "USER_LOGIN",
    Instant.now()
);

✔ Enforced immutability
✔ Clear intent: this is data, not behavior
✔ Perfect for events, projections, DTOs, and query models
✔ Eliminates 70–80% of POJO boilerplate

Best Practice:
Use records for value objects, not entities with lifecycle or identity mutation.


C#: record for Modern, Immutable Data Types

C# records bring value-based equality and non-destructive mutation to .NET.

Production Example: Configuration Snapshot

public record ServiceConfig(
    string ServiceName,
    string Endpoint,
    int TimeoutSeconds,
    bool EnableRetries
);

Practical Usage

var defaultConfig = new ServiceConfig(
    "BillingService",
    "https://billing.internal",
    30,
    true
);

var noRetryConfig = defaultConfig with { EnableRetries = false };

✔ Value-based equality
✔ Immutability by default
✔ Safe, expressive copying using with
✔ Ideal for configuration, DTOs, and messages

Best Practice:
Prefer record over class when the primary concern is data correctness, not identity.


Cross-Language Comparison

LanguageFeatureImmutabilityCopy SupportIdeal Use Case
Kotlindata classBy conventioncopy()Domain models, DTOs
Python@dataclassOptionalManual / replaceAPI schemas, configs
JavarecordEnforcedNew instanceValue objects, events
C#recordDefaultwithDTOs, snapshots

Final Thoughts: Design for Intent, Not Ceremony

Boilerplate is not just annoying—it’s a design smell. Modern data constructs allow you to:

  • Express intent clearly
  • Reduce maintenance risk
  • Improve correctness and readability
  • Align with immutability and functional principles

If a type primarily holds data, let the language work for you.

Less boilerplate.
More intent.
Better software.


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