java.lang · java.base · since Java 1.2

ThreadLocal

declaration

public class ThreadLocal<T>

Per-thread variable storage: each thread sees its own value. Historically used for non-thread-safe helpers and request context; ScopedValue is the modern successor.

Key methods

`static <S> ThreadLocal<S> withInitial(Supplier<S>)`	Create with a per-thread initializer.
`T get() / void set(T value)`	The calling thread's copy.
`void remove()`	Delete this thread's entry — mandatory hygiene in pooled threads.