How does Strings and string pool behave in multithreaded code?

In Java, strings are immutable objects, which means once a string is created, it cannot be changed. This immutability plays a crucial role in how strings behave in multithreaded environments. When multiple threads access a string concurrently, there is no risk of one thread modifying the string and affecting the other threads, as any modification results in the creation of a new string object.

The Java String Pool is a special storage area in the Java heap where string literals are stored. When a string is created as a literal, Java checks the string pool to see if an identical string is already present. If it is, Java returns a reference to the existing string. This behavior helps to save memory and improves performance, especially when dealing with the same string literals in a multithreaded scenario.

In a multithreaded context, this means that strings can be shared across threads without synchronization, ensuring both safety and efficiency. Nevertheless, caution is needed if any thread attempts to manipulate a string (for example, via concatenation) since these operations would create new strings and not modify the existing one.