Why Java String class is declared as final

Question

Can someone help me to understand why String class in Java is declared as final?

Answer 1

String class is made final in Java in order to make the String objects immutable. Making an object immutable helps in two ways:

1. Security: the system can hand out sensitive bits of read-only information without worrying that they will be altered
2. Performance: immutable data is very useful in making things thread-safe.

Answer 2

String is having a special features. where those features are not available in normal java classes. So if we extend the string class and allows the sub class to modify according to it. then there is no meaning of having special features . so to avoid that string has been made as final .so that we cannot extend the string class.