Scoped values

Definition

A scoped value (Java 25) shares data with the code you call, for example the current user, without passing it as a parameter. The value is fixed for the duration of one run and is safe to share with virtual threads, which makes it a cleaner replacement for ThreadLocal.

Example code

The current user, available to every method inside run()

class Demo {
    static final ScopedValue<String> USER = ScopedValue.newInstance();

    static void handleRequest() {
        System.out.println("Handling a request for " + USER.get());   // no parameter needed
    }

    public static void main(String[] args) {
        ScopedValue.where(USER, "asha").run(Demo::handleRequest);
        ScopedValue.where(USER, "ravi").run(Demo::handleRequest);
        System.out.println("bound outside run? " + USER.isBound());
    }
}

// Output:
// Handling a request for asha
// Handling a request for ravi
// bound outside run? false