String Buffer (String Maipulation) java.lang.StringBuffer

StringBuffer is a peer class of String that provides much of the functionality of strings.
String represents fixed-length, immutable character sequences while StringBuffer represents growable and writable character sequences.

Instantiate

• simple

  StringBuffer s = new StringBuffer();

• With fixed size (n)

  StringBuffer s = new StringBuffer(int n);

• With initial string (str)

  StringBuffer s = new StringBuffer(String str);

  ex: StringBuffer s = new StringBuffer("InfoSite");

Methods (s)

• length() - length of stringBuffer

  int n = s.length();

• capacity() - the total allocated capacity

  int n = s.capacity();

• append() - append text/number to the exisiting string

  s.append(String str);

  s.append(int num);

• insert() - is used to insert text/ character at the sepcified index poition

  s.insert(int index, String str);

  s.insert(int index, char ch);

• reverse() - Reverse the string

  s.reverse();

• delete() - delete sequence of character in range of start index to end-1 index

  s.delete(int startIndex, int endIndex);

  s.deleteCharAt(int index);

• replace() - replace sequence of character in range of start index to end-1 index

  s.replace(int startIndex, int endIndex,String replaceStr);

• appendCodePoint() - appends string represntation of the CodePoint argument

  s.appendCodePoint(int codePoint);

  ex: for int cp = 65, is 'A'

• codePointAt() - returns the characters ASCII (unicode) at the index

  int n = s.codePointAt(int index);

• charAt() - returns the character at index

  char ch = s.charAt(int index);

• getChars() - copies individual characters from begin to end into the char array from arrBegin index

  s.getChars(int Begin, int End, char[] array, int arrBegin);

• indexOf() - returns the index of the first occurrence of subString str

  s.indexOf(String str);

• lastIndexOf() - returns the index of the last occurrence of subString str

  s.lastIndexOf(String str);

• setCharAt() - replace character at the index

  s.setCharAt(int index, char ch);

• setlength() - change the length of stringBuffer

  s.setLength(int length);

• subSequence() - returns Char sequence in range of start index to end-1 index

  String str = s.subSequence(int start,int end);

• subSting() - returns sub string in range of start index to end-1 index

  String str = s.subString(int start); //extends till end of string

  String str = s.subString(int start,int end);

• toString() - returns a string representation of sequence

  String str = s.toString();

• trimToSize() - reduce capacity of stringBuffer to length of string

  s.trimToString();