How does final keyword behave in multithreaded code?

The `final` keyword in Java is used to declare constants, prevent method overriding, and prevent inheritance. In the context of multithreading, the behavior of `final` variables can significantly enhance the effectiveness of concurrent programming by ensuring that the values assigned to these variables are safely published and immutable after initialization.

When a variable is declared as `final`, it can only be assigned once. This means that once a `final` variable is initialized, it cannot be changed, thus providing thread safety for the variable. Any thread accessing this variable will see the initialized value after the variable is constructed.

For instance, when an object is constructed, its `final` fields are set. If a thread completes the construction of an object, and other threads access that object after construction, they will always see the `final` fields with their initialized values, thus preventing any visibility issues that could arise with regular mutable fields.