Java: String is final & immutable because

String is final & immutable because...

• String pool stores only one copy hence memory is saved
• Security: username & password like sensitive info received from external sources cannot modified in implementation (i.e. after/before validation
• Helps in Caching & Hashing i.e. hash value of the String is cached and returned (as it never changes)
• Above #1, #2 & #3, helps in improving the performance
• As strings are immutable, they are thread safe hence helps in synchronization