1. StringBuffer class  Alternative to String class  Can be used wherever a string is used  More flexible than String  Has three constructors and more than 30 methods for managing the buffer and modifying strings in the buffer  See page 266

2. Constructing a string buffer Three constructors  Public StringBuffer()  StringBuffer st = new StringBuffer();  Public StringBuffer(int length)  StringBuffer st2 = new StringBuffer(10);  Public StringBuffer(String str)  StringBuffer st3 = new StringBuffer(“Hello”);

3. Modifying string in the buffer Append at the end of a string Insert new contents at a specified position in a string buffer Replace characters in a string buffer

4. The StringTokenizer class java.util.StringTokenizer Used to break a string into pieces so that information contained in it cab be retrieved and processed. For example, a string “I am learning Java now”, you create an instance of a stringTokenizer class for the string and then retrieve individual words in the string by using methods in StringTokenizer

5. Constructors for StringTokenizer public StringTokenizer(String s, String delim, boolean returnTokens) Constructs a StringTokenizer for string s with specified delimiters. If returnTokens is true, the delimiters is returned as a token. Public StringTokenizer(String s, String delim) Constructs a Stringtokenizer for a string s with specified delimiters delim and the delimiter is not a token Public StringTokenizer(String s) Constructs a StringTokenizer for string s withh default delimiters, a space, tab, new line, and the delimiter is not a token

6. Methods in StringTokenizer int countTokens()  Return number of tokens remaining in the StringTokenizer boolean hasMoreTokens()  Return true if more token left, flase if no token left String nextToken()  Return the next token(string) stored in StringTokenizer String nextToken(String delim)  Return the next token(string) after reseting the delimiter to delim

7. In-class practice How do you create a string buffer from a string? How do you get the string from a string buffer? Declare a StringTokenizer for a string a with slash(/) as delimiter Write statements to reverse a string s using the revere method in the StringBuffer class

8. In-class practice What is the output of the following program import java.util.StringTokenizer; Class TestStringTokenizer{ public static void main(String[] arg){ String s= “I/am\learning Java.”; StringTokenizer st = new StringTokenizer(s, “/\.”); While(st.hasMoreTokens()) System.out.print(st.nextToken() + “ “); }}

9. Challenge Write a method that checks whether two strings are anagrams. Two strings are anagrams if they contain the same characters in any order. For example, “silent” and “listen” are anagrams. Public static boolean isAnagrams(String s1, String s2)