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13 LIBRARY
CLASSES
Learning Objectives
13.1 Primitive and Composite Data Types 13.2 Class as a Composite Data Type
13.3 Difference between Primitive and Composite Data Types 13.4 Introduction to Wrapper Classes
13.5 How to use Wrapper Classes? 13.6 Autoboxing and Unboxing
Till now, you have created various classes according to your requirement in the previous chapters. As you know, Java
totally depends on classes and objects. Did you know that Java also provides various predefined classes to do the task
quickly? Yes, it is true. You don't need to write a code for several tasks. These predefined classes provided by Java are
known as library classes. These classes are available to use in the form of packages. A package is a collection of similar
types of classes and sub packages.
Some of the commonly used packages are as follows:
Java Packages Purposes
java.lang Used for string manipulations
java.io Used for input/output operations
java.util Used for input through scanner class
Java.math Used for mathematical operations
You already learnt that to use the classes of a package, you need to import the package into your program. To include
the packages in a program, the import keyword is used. Syntax to import a package is:
import <package name>;
To include the classes of the package java.util, we have to use the following command:
import java.util.*;
Where, * allows you to import all the classes of the java.util package.
13.1 PRIMITIVE AND COMPOSITE DATA TYPES
Primitive data types are in-built data types developed by the developer of the language. They are predefined by the
Java compiler. A primitive data type stores single value at a time. Java provides eight different primitive data types
which are byte, short, char, int, float, double, long and boolean. You have already learnt about these data types in the
previous chapters.
326326 Touchpad Computer Applications-X

