Why String is Immutable or Final in Java?

Answer 1

The string is Immutable in Java because String objects are cached in String pool. Since cached String literals are shared between multiple clients there is always a risk, where one client's action would affect all another client.

Answer 2

String is shared on different area like file system, networking connection, database connection , having immutable string allows you to be secure and safe because no one can change reference of string once it gets created. if string had been mutable anyone can surpass the security be logging in someone else name and then later modifying file belongs to other.