Convert Nested JSON Objects to Linked Java POJOs

Modeling Nested JSON in Java

Real-world JSON almost always contains nested objects. The generator extracts each nested object into its own class, named after the parent key in PascalCase, and the enclosing class references it via a typed field.

Example JSON

{
  "id": 1,
  "name": "Acme Corp",
  "address": {
    "street": "123 Main St",
    "city": "Springfield",
    "zip": "62704"
  }
}

Generated Java POJOs

package com.example.model;

public class Company {
    private Integer id;
    private String name;
    private Address address;
    // getters/setters omitted for brevity
}

public class Address {
    private String street;
    private String city;
    private String zip;
    // getters/setters omitted for brevity
}

How the Generator Names Nested Classes

The class name comes from the JSON key, converted with PascalCase rules:

• address → Address
• shipping_address → ShippingAddress
• billing-info → BillingInfo
• contactDetails → ContactDetails

If two nested objects would resolve to the same class name, a numeric suffix is appended automatically: Address, Address2, Address3.

Nesting Depth

There is no fixed depth limit. Three- or four-level nesting (Order → LineItem → Product → Pricing) generates four classes, each linked through typed references.

Deserialization with Jackson

ObjectMapper mapper = new ObjectMapper();
Company company = mapper.readValue(json, Company.class);
String city = company.getAddress().getCity();

Jackson walks the type graph automatically — no extra configuration is needed for nested POJOs.

Tips for Reuse

If the same logical type (e.g., Address) appears under multiple parents in the source JSON, the generator currently produces independent classes for each occurrence. After generation, you can manually consolidate them into a single shared class to avoid duplication.