Saturday, 16 June 2018

Why String class is immutable?



Strings implemented as final or immutable objects.It provides lot of advantages in its usage. Below are some advantages of String Immutability in Java


  • Immutable objects are thread-safe. Two threads can both work on an immutable object at the same time without any possibility of conflict.
  • Security: the system can pass on sensitive bits of read-only information without worrying that it will be altered
  • You can share duplicates by pointing them to a single instance.
  • You can create substrings without copying. You just create a pointer into an existing base String guaranteed never to change. Immutability is the secret that makes Java substring implementation very fast.
  • Immutable objects are good fit for becoming Hashtable keys. If you change the value of any object that is used as a hash table key without removing it and re-adding it you will lose the object mapping.
  • Since String is immutable, inside each String is a char[] exactly the correct length. Unlike a StringBuilder there is no need for padding to allow for growth.
  • If String were not final, you could create a subclass and have two strings that look alike when "seen as Strings", but that are actually different.

Enjoy Reading.

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