Generate Java POJOs with List<T> Fields from JSON Arrays

JSON Arrays as Java List

JSON arrays map directly to java.util.List<T>. The generator inspects the array contents to choose the element type T.

Homogeneous Arrays of Primitives

{
  "name": "playlist",
  "track_ids": [101, 102, 103]
}

public class Playlist {
    private String name;
    private List<Integer> trackIds;
    // accessors
}

Arrays of Objects

{
  "id": 1,
  "items": [
    { "sku": "A1", "qty": 2 },
    { "sku": "B2", "qty": 1 }
  ]
}

public class Order {
    private Integer id;
    private List<Item> items;
}

public class Item {
    private String sku;
    private Integer qty;
}

The first element of the array drives the class generation. Subsequent elements are assumed to share the same shape — if they do not, you may need to merge fields manually.

Mixed-Type Arrays

{ "values": [1, "two", true] }

public class Root {
    private List<Object> values;
}

When the elements have different types, the generator falls back to List<Object>. You can refine this manually using a sealed interface or wrapper class for type-safe access.

Empty Arrays

{ "tags": [] }

private List<Object> tags;

The element type is unknown, so the generator emits List<Object>. Replace with the correct type after consulting your API contract.

Required Import

The generator automatically adds:

import java.util.List;

Why List and not Array?

Arrays in Java are fixed-size and have awkward generics support (new T[] is a compile error). List<T> integrates cleanly with the Collections framework, streams, and most JSON libraries. Jackson, Gson, and Moshi all deserialize JSON arrays into List by default when the field type is List.