Java: String-String Buffer-String Builder

Sunday, June 16, 2013

Hi All,

Welcome to Java-recent.,a blog explaining Java related concepts.

In this post we will discuss about important core Java concept- Differences between String ,String Buffer,String Builder .

Lets see the basic info

String :-

· represents sequence of characters,which cannot be modified(Immutable),If we modify

a value, a new Object will be created.

· As they are immutable they can be shared across objects

Different ways of declaring String variables are:-

String blogName="Java-recent";

String blogName=new String("Java-recent");

String Buffer:-

implements mutable(can be modified) sequence of characters
String buffer is thread safe(Synchronized),means at any point of time only single thread can access
Uses append() for concatenating Strings,which is efficient than String + operator

StringBuffer blogName=new StringBuffer("Java-recent");

Stirng Builder :-

implements mutable sequence of characters
String Builder is not thread safe
Introduced in Java5
String Builder is faster than String buffer as it is not Synchronized by default.

StringBuilder blogName=new StringBuilder("Java-recent");

After brief overview now lets move to most important differences among them

String	String Buffer	String Builder
Immutable	Mutable	Mutable
Thread safe	Thread safe	Not Thread safe
Uses + for concatenating Strings	Uses append method	Uses append method
Widely used as key in hashmaps	Widely used if there are lot of modifications on a String value	Widely used if there are lot of modifications on a String value

Disadvantages of using String :-

As String is immutable ,modification of a String like converting to upper case,substring etc. actions will always create new objects
String modification should be done sparingly
Concatenating String using '+' operator is costlier than using Append method in String Buffer and String Builder.,Reason behind this is Append () will produce most optimized byte code than + operator

when there is use of repeated Strings in a particular class its better to use String literals,because they will be Stored in String literal pool

Happy Learning

Please provide your valuable comments on this article and share it across your network.

Java