Friday, 25 November 2016

Program to show use of some 'StringBuffer' class methods

StringBuffer class is like a String, but can be modified. StringBuffer class is mutable. StringBuffer is fast and consumes less memory when you concat strings. For example,
// Constructs string buffer with no characters in it 
// and an initial capacity of 16 characters.
StringBuffer  s1 = new StringBuffer( );    


// Constructs a string buffer with no characters in it and the specified 
// initial capacity to 5.
StringBuffer  s2 = new StringBuffer(5);

// Constructs a string buffer that contains the three characters.  
// The initial capacity of the string buffer is 16 plus 
// the length of the "abc" string in short it is 19. 
StringBuffer s3 = new StringBuffer("abc");

We have used the following methods of StringBuffer class:
  • capacity( ) : It returns the current capacity.
  • lastIndexOf(String str) : It returns the index within this string of the rightmost occurrence of the specified substring.
  • reverse( ) : It causes the character sequence to be replaced by the reverse of the sequence.

class UsingStringBufferMethods {

 public static void main(String[] args) {
  StringBuffer s = new StringBuffer(5);
  System.out.println("String capacity : "+s.capacity());
  s = new StringBuffer("Hello Java");
  System.out.println("String Given : "+s);
  System.out.println("Last index of 'Java' is : " + s.lastIndexOf("Java"));
  StringBuffer strRev = s.reverse();
  System.out.println("Now String is : "+s);
  System.out.println("Reverse String : "+strRev);
C:\>java UsingStringBufferMethods
String capacity : 5
String Given : Hello Java
Last index of 'Java' is : 6
Now String is : avaJ olleH
Reverse String : avaJ olleH

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