Implementation:SeleniumHQ Selenium ImmutableCapabilities

Knowledge Sources	SeleniumHQ_Selenium Selenium Documentation
Domains	WebDriver, Capabilities
Last Updated	2026-02-12 00:00 GMT

Overview

Concrete tool for representing a read-only, thread-safe set of browser capabilities provided by the Selenium WebDriver library.

Description

ImmutableCapabilities is an immutable implementation of the Capabilities interface that wraps capability key-value pairs in an unmodifiable TreeMap. It pre-computes its hash code at construction time for efficient use in hash-based collections. The class provides multiple convenience constructors accepting from zero up to five key-value pairs, as well as constructors from an existing Capabilities instance or a Map, and a static copyOf factory method that avoids redundant copying when the input is already immutable.

Usage

Import and use ImmutableCapabilities when you need a guaranteed-immutable snapshot of capabilities, for example when storing capabilities as map keys, passing them across threads, or when a method contract requires that capabilities cannot be modified after creation.

Code Reference

Source Location

• Repository: SeleniumHQ_Selenium
• File: java/src/org/openqa/selenium/ImmutableCapabilities.java

Signature

public class ImmutableCapabilities implements Capabilities

Import

import org.openqa.selenium.ImmutableCapabilities;

I/O Contract

Inputs

Name	Type	Required	Description
(none)		No	No-arg constructor creates an empty immutable capabilities instance
k, v	String, Object	Yes	Single key-value pair constructor (up to 5 pairs supported via overloaded constructors)
other	Capabilities	Yes	Copy constructor; creates an immutable snapshot from an existing Capabilities instance
capabilities	Map<?, ?>	Yes	Map constructor; keys must be String instances, values must be non-null

Outputs

Name	Type	Description
getCapability(name)	Object (nullable)	Returns the value for the given capability name, or null if not present
asMap()	Map<String, Object>	Returns the unmodifiable internal map of all capabilities
copyOf(capabilities)	ImmutableCapabilities	Static factory that returns the input if already immutable, otherwise creates a new copy

Usage Examples

// Create with key-value pairs
ImmutableCapabilities caps = new ImmutableCapabilities(
    "browserName", "chrome",
    "platformName", "LINUX"
);

// Create from an existing Capabilities object
MutableCapabilities mutable = new MutableCapabilities();
mutable.setCapability("browserName", "firefox");
ImmutableCapabilities snapshot = new ImmutableCapabilities(mutable);

// Use the static copyOf factory (avoids redundant copying)
ImmutableCapabilities copy = ImmutableCapabilities.copyOf(snapshot);
// copy == snapshot (same instance, since already immutable)

// Create from a Map
Map<String, Object> map = Map.of("browserName", "edge");
ImmutableCapabilities fromMap = new ImmutableCapabilities(map);

Related Pages

• Principle:SeleniumHQ_Selenium_Browser_Options_Configuration