Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Why String class is immutable or final in Java?
The string is immutable means that we cannot change the object itself, but we can change the reference to the object. The string is made final to not allow others to extend it and destroy its immutability.
Security Parameters are typically represented as String in network connections, database connection URLs, usernames/passwords, etc. If it was mutable, these parameters could be changed easily.
Synchronization and Concurrency making String immutable automatically makes them thread safe thereby solving the synchronization issues.
Caching when compiler optimizes our String objects, it seems that if two objects have the same value (a =" test", and b =" test") and thus we need only one string object (for both a and b, these two will point to the same object).
Class loading String is used as arguments for class loading. If mutable, it could result in the wrong class being loaded (because mutable objects change their state).
Example
public class StringImmutableDemo {
public static void main(String[] args) {
String st1 = "Tutorials";
String st2 = "Point";
System.out.println("The hascode of st1 = " + st1.hashCode());
System.out.println("The hascode of st2 = " + st2.hashCode());
st1 = st1 + st2;
System.out.println("The Hashcode after st1 is changed : "+ st1.hashCode());
}
}
Output
The hascode of st1 = -594386763 The hascode of st2 = 77292912 The Hashcode after st1 is changed : 962735579
7K+ Views
