String in java

Collection of character is refer to us as a string.

Java supports two types of string

  1. Immutable string
  2. Mutable string

Immutable string

All the string whose value can not be changed once they are initialized are refereed as Immutable string. Immutable string can be created in two ways.

type 1 : String s = " Hello ";
type 2 : String s = new String(" Hello ");

here ” “  double quotes must be used while initializing string.

Note:In java charater level access is not provided so the string can not be changed after initialization, so they are called as Immutable.
Example: System.out.println(s[0]);     // this will give error

if data in the string is continuously changing then we should not use immutable string in program , instead we should use mutable string as follows.

Mutable string

All those string whose values can be changed after initialization is refer to us as a Mutable string.

To declare the string any one of the following in-built class can be used.

StringBuffer or StringBuilder

Example :

class MutableDemo{
    public static void main(String args[]){
        StringBuffer s = new StringBuffer(" Hello ");
        s.append("World"); // append method used to modify string

Output: Hello
        Hello world


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