java 33 lines · 7 steps

Deep-copying objects via Jackson serialization

A utility that clones any object by serializing it to JSON bytes and reading it back into a fresh instance.

Explained by highlit
Intermediate serialization deep-copy generics immutability utility-class
1public final class DeepCopier {
2 
3 private static final ObjectMapper MAPPER = new ObjectMapper()
4 .registerModule(new JavaTimeModule())
5 .findAndRegisterModules();
6 
7 private DeepCopier() {
8 }
9 
10 public static <T> T copy(T source, Class<T> type) {
11 if (source == null) {
12 return null;
13 }
14 try {
15 byte[] bytes = MAPPER.writeValueAsBytes(source);
16 return MAPPER.readValue(bytes, type);
17 } catch (IOException e) {
18 throw new IllegalStateException("Failed to deep-copy " + type.getSimpleName(), e);
19 }
20 }
21 
22 public static <T> T copy(T source, TypeReference<T> typeRef) {
23 if (source == null) {
24 return null;
25 }
26 try {
27 byte[] bytes = MAPPER.writeValueAsBytes(source);
28 return MAPPER.readValue(bytes, typeRef);
29 } catch (IOException e) {
30 throw new IllegalStateException("Failed to deep-copy value", e);
31 }
32 }
33}
01 / 01
STEP 01

Walkthrough

Space play ←→ step click any line
Three takeaways
  1. 1Round-tripping through a serializer is a generic way to deep-copy without writing per-class clone logic.
  2. 2A shared, immutable ObjectMapper is thread-safe and worth reusing as a static singleton.
  3. 3TypeReference overloads let you preserve generic type information that a plain Class token would erase.

Related explainers

java 
@Component
public class OrderRecoveryHandler {
 
    private final RabbitTemplate rabbitTemplate;

Dead-letter recovery with Spring AMQP

dead-letter-queue retry exponential-backoff
Advanced 9 steps
php 
final class Route
{
    private string $regex;
    private array $paramNames = [];

Compiling route patterns into regex in PHP

routing regex parsing
Intermediate 8 steps
java 
@Component
public class CorrelationIdWebFilter implements WebFilter, Ordered {
 
    public static final String CORRELATION_ID_HEADER = "X-Correlation-Id";

Correlation IDs in a Spring WebFlux filter

reactive web filter correlation id
Advanced 7 steps
python 
from flask import Blueprint, request, url_for, jsonify, abort
from flask.views import MethodView
 
from .models import Article, db

Building a paginated JSON API with Flask MethodView

rest-api pagination class-based-views
Intermediate 10 steps
ruby 
module DeepImmutable
  module_function
 
  def deep_freeze(obj)

Deep-freezing config with recursive immutability

immutability recursion deep-copy
Intermediate 8 steps
java 
package com.example.time;
 
import java.time.Duration;
import java.time.Instant;

Adding ISO-8601 durations across time zones in Java

date-time iso-8601 parsing
Intermediate 7 steps

Share this explainer

Here's the card — post it anywhere.

Deep-copying objects via Jackson serialization — share card
Made with highlit — turn any snippet into a walkthrough like this in about a minute.
Explain your code