Page 247 - computer science (868) class 11
P. 247

9.6 JAVA LIBRARY CLASS
                 Some methods are provided by Java for making coding easy. These in-built methods are available in the library class
                 which can be imported into the code dynamically at runtime. This library further contains packages.

                 Packages are a group of similar type of classes, interfaces and sub-packages, which contains some built-in classes
                 containing methods, that are required during coding. Packages can be categorized into two, namely, built-in packages
                 and user-defined packages.

                 There are many built-in packages that are commonly used such as java, lang, awt, javax, swing, net, io, util, sql, etc.
                 To include a package in a program, the syntax is

                    import java.<packagename>.<classname>;
                 For examples:

                    import java.util.*;
                    import java.io.*;
                 The ”lang” package is the default package in Java and when we use it, we do not need to use the ‘import’ command
                 as it is automatically executed.



                              Let’s Revisit

                      ♦  Strings refer to the combination of different characters including alphabets, digits, punctuators and/or special symbols.

                      ♦  The Character is a built-in class in Java that provides various methods to manipulate characters.
                      ♦  The StringBuffer class is used to create sufficient space in the memory to store a String.
                      ♦  The StringTokenizer class splits the given string into tokens (sequence of characters except delimiters) or words.








                                                              MIND DRILL





                      Solved Questions



                 A.  Tick ( ) the correct answer:

                    1.  "India" is an example of a ………………… .
                       a.  char                                        b.  string
                       c.  Both a and b                                d.  None of these
                    2.  What data type does Character.isLetter(char) return?
                       a.  boolean                                     b.  char
                       c.  String                                      d.  int
                    3.  What is the starting value of the length() method?
                       a.  0                                           b.  1
                       c.  2                                           d.  3
                    4.  For a string variable, which method returns the character at the given index?
                       a.  length()                                    b.  indexOf()
                       c.  charAt()                                    d.  None of these




                                                                                                                       245
                                                                                                              Strings  245
   242   243   244   245   246   247   248   249   250   251   252