Hi vijay


Java provides the StringBuffer and String classes, and the String class is used to manipulate character strings that cannot be changed. Simply stated, objects of type String are read only and immutable. The StringBuffer class is used to represent characters that can be modified.

The significant performance difference between these two classes is that StringBuffer is faster than String when performing simple concatenations.

StringBuffer is mainly used for the dynamic string concatenation which enhances the performance. A string buffer implements a mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls.

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import java.io.*;
import java.io.IOException;

public class stringBuffer{
public static void main(String[] args) throws Exception{
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String str;
try{
System.out.print("Enter your name: ");
str = in.readLine();
str += ", This is the example of SringBuffer class and it's function.";

//Create a object of StringBuffer class
StringBuffer string = new StringBuffer();
string.append(str);
System.out.println(string);
string.delete(0,str.length());

//append()
string.append("Welcome");
string.append(" to"); //print HelloWorld
string.append(" Roseindia");
string.append(".");
System.out.println(string);


}
catch(StringIndexOutOfBoundsException e){
System.out.println(e.getMessage());
}
}
}

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Read for more information.

http://www.roseindia.net/java/beginners/StringBuffer.shtml

One more difference between String and StringBuffer in Java is that StringBuffer is not String and can not be used when later is expected.