BASIC ELEMENTS OF JAVA - Java Programming: From Problem Analysis to Program Design - page 71

Note that the single quote can also be printed without using the escape sequence.
Therefore, the preceding statement is equivalent to the following output statement:

System.out.println("The tab character is represented as '\\t'");
The output of the statement:

2

System.out.println("The string \"Sunny\" contains five characters");

is:

The string "Sunny" contains five characters

To access a Java program that shows the effect of the statements in Example 2-23,
download Additional Student Files from www.cengagebrain.com. (The program is named
Example2_23.java .)

Packages, Classes, Methods, and the import
Statement
Only a small number of operations, such as arithmetic and assignment operations, are
explicitly defined in Java. Many of the methods and identifiers needed to run a Java
program are provided as a collection of libraries, called packages. A package is a
collection of related classes. Moreover, every package has a name.
In Java, class is a broadly used term. The term class is used to create Java programs, either
application or applet; it is used to group a set of related operations; and it is used to allow
users to create their own data types. For example, there are various mathematical
operations, such as determining the absolute value of a number, determining one number
raised to the power of another number, and determining the logarithm of a number. Each
of these operations is implemented using the Java mechanism of methods. Think of a
method as a set of instructions designed to accomplish a specific task. For example, the
name of the method implementing the operation of one number raised to the power of
another number is pow . This and other mathematical methods are contained in the class
Math . The name of the package containing the class Math is java.lang .
The package java.util contains the class Scanner . This class contains the methods
nextInt , nextDouble , next , and nextLine for inputting data into a program. In the
next section, you will learn how class(es) are used to create a Java application program.

To see the complete definitions of the (predefined) Java classes, such as String , Math ,
and Scanner , as well as the class hierarchy, you can visit the Web site http://
java.sun.com/javase/7/docs/api/.