Differences between String and StringBuffer

Java Server Side Programming Programming

String is an immutable class and its object can’t be modified after it is created but definitely reference other objects. They are very useful in multithreading environment because multiple threads can’t change the state of the object so immutable objects are thread safe.

String buffer is mutable classes which can be used to do operation on string object such as reverse of string, concating string and etc. We can modify string without creating new object of the string. String buffer is also thread safe.

Also, string concat + operator internally uses StringBuffer or StringBuilder class. Below are the differences.

Sr. No.	Key	String	StringBuffer
1	Basic	String is an immutable class and its object can’t be modified after it is created	String buffer is mutable classes which can be used to do operation on string object
2	Methods	Methods are not synchronized	All methods are synchronized in this class.
3	Performance	It is fast	Multiple thread can’t access at the same time therefore it is slow
4.	Memory Area	I f a String is created using constructor or method then those strings will be stored in Heap Memory as well as SringConstantPool	Heap Space

Example of String

public class Main {
   public static void main(String args[]) {
      String s1 = "Hello Tutorials Point";
      String upperCase = s1.toUpperCase();
      System.out.println(upperCase);
   }
}

Example of StringBuffer

public class StringBufferExample{
   public static void main(String[] args){
      StringBuffer buffer=new StringBuffer("Hi");
      buffer.append("Java 8");
      System.out.println("StringBufferExample" +buffer);
   }
}