JSON to Java Converter

How JSON maps to Java types

The tool reads the top-level keys of a JSON object and writes one private field with a getter and setter per key. Types come from the sample values you paste:

• number becomes Double, boolean becomes Boolean and string becomes String.
• null, arrays and nested objects become Object.
• Getter and setter names capitalize the first letter of the key (key id gives getId and setId).

JSON to Java example

Input:

{"id":1,"name":"Ada","active":true,"address":{"city":"London"},"tags":["math"]}

// Java output
public class Root {
    private Double id;
    public Double getId() { return id; }
    public void setId(Double id) { this.id = id; }
    private String name;
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    // ...the same pattern for active (Boolean), address (Object) and tags (Object)
}

What to review before you use the Java output

• Paste a JSON object, not a bare array. The tool walks the top-level keys, so an array root produces meaningless index names.
• Nested objects and arrays are not expanded into their own types. In the example, address and tags both fall back to a generic type, so write those types by hand.
• One sample cannot show which fields are optional or which numbers are integers. Numbers are always mapped to a floating-point type.
• Keys that are not valid Java identifiers, such as first-name, are written as-is and will not compile. Rename them.
• The tool does not add Jackson or Gson annotations or package and import lines.

Related: JSON to Kotlin, JSON to C#, JSON Validator, JSON Formatter