JSON to Java

About the JSON to Java

The JSON to Java converter generates Java records (Java 16+) or classic classes with getters and setters from a JSON sample. Arrays become List types, nested objects become their own types, and Jackson @JsonProperty annotations are added where a Java name differs from the JSON key.

Conversion happens in your browser, so your files and records stay private.

How to use the JSON to Java

1. Paste a JSON sample and set the root type name.
2. Choose records or classes, and whether to add Jackson annotations.
3. Copy the code. Only the root type is public, so move other types into their own files if your project needs one public type per file.

Example

{
  "id": 7,
  "fullName": "Grace Hopper",
  "email": null,
  "roles": ["admin"],
  "team": { "name": "Compilers", "size": 4 },
  "projects": [
    { "name": "COBOL", "year": 1959 },
    { "name": "A-0", "year": 1952, "archived": true }
  ]
}

import java.util.List;

public record User(
    long id,
    String fullName,
    Object email,
    List<String> roles,
    Team team,
    List<Project> projects
) {}

record Project(
    String name,
    long year,
    Boolean archived
) {}

record Team(
    String name,
    long size
) {}

Common mistakes

• Primitives for nullable values. A long or boolean cannot be null, so a missing value silently becomes 0 or false. Keep the boxed types the converter chose for fields that were null or missing.
• Several public types in one file. Java allows one public top-level type per file. Move each type into its own file, or nest them as static classes inside the root type.

Works well with the JSON to Java

• JSON Formatter: tidy and check the JSON before generating types.
• JSON to TypeScript: generate matching TypeScript interfaces for the front end.
• JSON Validator: find syntax errors in the sample first.

Frequently asked questions