Primitive Converter

JavetPrimitiveConverter is the basic converter that only takes care of primitive values. It is the base class of all other converters and handles the most common type conversions. It is optimized for performance with type checks ordered by statistical frequency.

From Java to JavaScript

Java	JavaScript
boolean/Boolean	boolean
byte/Byte	int
char/Character	string
double/Double	number
float/Float	number
int/Integer	int
long/Long/BigInteger	bigint
short/Short	int
String	string
ZonedDateTime	Date
null	null

Any unrecognized Java type is converted to undefined.

Optional Types

Optional, OptionalInt, OptionalDouble, and OptionalLong are supported. If the optional is present, the inner value is converted recursively. If empty, the result is null.

// Optional with value → converted inner value
converter.toV8Value(v8Runtime, Optional.of(123));       // → V8ValueInteger(123)
converter.toV8Value(v8Runtime, OptionalLong.of(100L));  // → V8ValueLong(100)

// Empty optional → null
converter.toV8Value(v8Runtime, Optional.empty());       // → V8ValueNull
converter.toV8Value(v8Runtime, OptionalInt.empty());    // → V8ValueNull

From JavaScript to Java

JavaScript	Java
boolean	boolean
int	int
bigint	long/BigInteger
number	double
string	String
Date	ZonedDateTime
null	null
undefined	null

Any unrecognized V8 value type (objects, arrays, functions, etc.) is returned as the raw V8Value instance.

Note

• JavetPrimitiveConverter is typically not used directly. Use JavetObjectConverter (the default) for most use cases.

• If bigint falls in the range of long, it is converted to long. Otherwise, it is converted to BigInteger.

• Both null and undefined from JavaScript are converted to Java null.

Numeric Widening and Narrowing

When a JavaScript value is passed to a Java callback method, Javet performs automatic type coercion:

• int and bigint can be narrowed to byte, short, or widened to long, float, double.

• A single-character string can be converted to char. Multi-character strings are silently truncated to the first character.

• Both boxed (Integer) and unboxed (int) parameter types are supported in callbacks.