What is Immutable Objects ?
When you have a reference to an instance of an object, the contents of that instance cannot be altered
class ImmutableString { public static void main(String[] args) { String myString = new String("I am living in India"); System.out.println( myString ); myString.replaceAll( "India" , "USA" ); System.out.println( myString ); } }
Output of Program :
I am living in India I am living in India
Explanation : Immutable String Objects
In the above example, we can see that
myString.replaceAll( "India" , "USA" );
it will create another string i.e -
I am living in USA
though object is created for “I am living in USA” string but reference variable “myString” is still not referring to new string. We need to specify the reference explicitly using following assignment -
myString = myString.replaceAll( "India" , "USA" );
class ImmutableString { public static void main(String[] args) { String myString = new String("I am living in India"); System.out.println( myString ); myString = myString.replaceAll( "India" , "USA" ); System.out.println( myString ); } }
and output will be like this -
I am living in India I am living in USA
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