Project Valhalla: Bringing Value Types to Java


Project Valhalla is a long-term initiative within the OpenJDK community that aims to introduce value types to the Java programming language. The project’s primary goal is to enhance the performance and memory efficiency of Java by providing a more flexible and efficient way to represent data. Value types are a significant departure from the traditional object-oriented approach, offering a new mechanism for handling certain types of data.

Key Objectives:

Introduction of Value Types:

  • The central objective of Project Valhalla is to introduce value types as a new kind of class in Java. Value types are designed to represent simple, immutable data without the overhead of object-oriented features.

Performance Improvement:

  • Value types aim to improve the performance of Java applications by reducing the memory footprint and enhancing data locality. This is particularly beneficial for scenarios where large amounts of data need to be processed efficiently.

Enhanced Data Representation:

  • Project Valhalla seeks to provide a more efficient representation of data in memory. Value types can be densely packed, leading to improved cache locality and reduced memory consumption.

Compatibility with Existing Code:

  • The project is committed to maintaining backward compatibility with existing Java code. This ensures a smooth transition for developers and allows them to adopt value types incrementally.

Benefits of Project Valhalla:

Memory Efficiency:

  • Value types allow for more efficient representation of data in memory, especially for scenarios involving large datasets. This can lead to significant memory savings and improved application performance.

Improved Performance:

  • By reducing the memory footprint and improving data locality, value types contribute to better performance in terms of both execution speed and resource utilization.


  • Project Valhalla is designed to be backward compatible with existing Java code. Developers can choose to adopt value types selectively in areas where performance improvements are crucial.

Versatility in Data Representation:

  • Value types provide a more versatile way to represent data, allowing developers to choose between reference types and value types based on the specific characteristics of the data they are working with.

Usage Examples (Conceptual):

public class Point {
    // Declaring a value type
    public value class Coordinates {
        double x;
        double y;

    // Using the value type in the main class
    Coordinates coordinates;

    public Point(double x, double y) {
        // Creating an instance of the value type
        this.coordinates = new Coordinates(x, y);

    // Other methods and fields in the Point class
    // ...


Project Valhalla represents a significant evolution in the Java language, introducing the concept of value types to address performance and memory efficiency challenges. By providing a more flexible and efficient way to handle certain types of data, Project Valhalla aims to empower developers to build high-performance Java applications with reduced memory overhead. As the project progresses, developers can anticipate more efficient data representation and improved performance in scenarios where value types are applied.