slide 1: EASY WEB SOLUTION
Instructor: Lavi Gupta 09803266066
slide 2:
Instructor: LAVI GUPTA M.T ech Computers
◦ Ofce: 351 TriCity PLAZZA Adj. Sec-20
Panchkula
◦ Ofce Phone: 9803266066 9501922388
◦ Email: techlavigmail.com
◦ Ofce hours: Monday T o Fridays 10-7pm
Or by appointment call: 09803266066
Instructor: Lavi Gupta 09803266066
slide 3:
Lecture: MWF 01:00 PM – 02:10 PM
Lab: W 02:30 PM - 04:20 PM
Instructor: Lavi Gupta 09803266066
slide 4:
Midterm: 20
Final: 25
Programming Projects: 40
Homework and labs: 15
Instructor: Lavi Gupta 09803266066
slide 5:
Object-Oriented Software Development
◦ problem solving
◦ program design implementation and testing
◦ object-oriented concepts
classes
objects
encapsulation
inheritance
polymorphism
◦ graphical user interfaces
Instructor: Lavi Gupta 09803266066
slide 6: •
The Java Programming Language
•
Program Development
•
Object-Oriented Programming
Instructor: Lavi Gupta 09803266066
slide 7:
A programming language specifes the words
and symbols that we can use to write a program
A programming language employs a set of rules
that dictate how the words and symbols can be
put together to form valid program statements
The Java programming language was created by
Sun Microsystems Inc.
It was introduced in 1995 and its popularity has
grown quickly since
Instructor: Lavi Gupta 09803266066
slide 8:
In the Java programming language:
◦ A program is made up of one or more classes
◦ A class contains one or more methods
◦ A method contains program statements
These terms will be explored in detail
throughout the course
A Java application always contains a method
called main
Instructor: Lavi Gupta 09803266066
slide 9: public class Lincoln
//-----------------------------------------------------------------
// Prints a presidential quote.
//-----------------------------------------------------------------
public static void main String args
System.out.println "A quote by Abraham Lincoln:"
System.out.println "Whatever you are be a good one."
Instructor: Lavi Gupta 09803266066
slide 10: public class MyProgram
// comments about the class
class header
class body
Comments can be placed almost anywhere
Instructor: Lavi Gupta 09803266066
slide 11: public class MyProgram
// comments about the class
public static void main String args
// comments about the method
method header
method body
Instructor: Lavi Gupta 09803266066
slide 12:
Comments in a program are called inline
documentation
They should be included to explain the
purpose of the program and describe
processing steps
They do not afect how a program works
Java comments can take three forms:
// this comment runs to the end of the line
/ this comment runs to the terminating
symbol even across line breaks /
/ this is a javadoc comment /
Instructor: Lavi Gupta 09803266066
slide 13:
Identifers are the words a programmer uses in a
program
An identifer can be made up of letters digits the
underscore character _ and the dollar sign
Identifers cannot begin with a digit
Java is case sensitive - Total total and
TOTAL are diferent identifers
By convention programmers use diferent case
styles for diferent types of identifers such as
◦ title case for class names - Lincoln
◦ upper case for constants - MAXIMUM
Instructor: Lavi Gupta 09803266066
slide 14:
The Java reserved words:
abstract
assert
boolean
break
byte
case
catch
char
class
const
continue
default
do
double
else
enum
extends
false
final
finally
float
for
goto
if
implements
import
instanceof
int
interface
long
native
new
null
package
private
protected
public
return
short
static
strictfp
super
switch
synchronized
this
throw
throws
transient
true
try
void
volatile
while
Instructor: Lavi Gupta 09803266066
slide 15:
Spaces blank lines and tabs are called
white space
White space is used to separate words and
symbols in a program
Extra white space is ignored
A valid Java program can be formatted
many ways
Programs should be formatted to enhance
readability using consistent indentation
Instructor: Lavi Gupta 09803266066
slide 16: public class Lincoln2public static void
mainStringargs
System.out.println"A quote by Abraham
Lincoln:"
System.out.println"Whatever you are be a
good one."
Instructor: Lavi Gupta 09803266066
slide 17: The Java Programming Language
Program Development
Object-Oriented Programming
Instructor: Lavi Gupta 09803266066
slide 18:
The mechanics of developing a program
include several activities
◦ writing the program in a specifc programming
language such as Java
◦ translating the program into a form that the
computer can execute
◦ investigating and fxing various types of errors
that can occur
Software tools can be used to help with all
parts of this process
Instructor: Lavi Gupta 09803266066
slide 19:
Each type of CPU executes only a
particular machine language
A program must be translated into
machine language before it can be
executed
A compiler is a software tool which
translates source code into a specifc
target language
Often that target language is the machine
language for a particular CPU type
The Java approach is somewhat diferent
Instructor: Lavi Gupta 09803266066
slide 20:
The Java compiler translates Java source code
into a special representation called bytecode
Java bytecode is not the machine language for
any traditional CPU
Another software tool called an interpreter
translates bytecode into machine language and
executes it
Therefore the Java compiler is not tied to any
particular machine
Java is considered to be architecture-neutral
Instructor: Lavi Gupta 09803266066
slide 21: Java source
code
Machine
code
Java
bytecode
Bytecode
interpreter
Bytecode
compiler
Java
compiler
Instructor: Lavi Gupta 09803266066
slide 22:
There are many programs that support the
development of Java software including:
◦ Sun Java Development Kit JDK
◦ Sun NetBeans
◦ IBM Eclipse
◦ Borland JBuilder
◦ MetroWerks CodeWarrior
◦ BlueJ
◦ jGRASP
Though the details of these environments
difer the basic compilation and execution
process is essentially the same
Instructor: Lavi Gupta 09803266066
slide 23:
The syntax rules of a language defne how we
can put together symbols reserved words and
identifers to make a valid program
The semantics of a program statement defne
what that statement means its purpose or role
in a program
A program that is syntactically correct is not
necessarily logically semantically correct
A program will always do what we tell it to do
not what we meant to tell it to do
Instructor: Lavi Gupta 09803266066
slide 24:
A program can have three types of errors
The compiler will fnd syntax errors and other basic
problems compile-time errors
◦ If compile-time errors exist an executable version of the
program is not created
A problem can occur during program execution
such as trying to divide by zero which causes a
program to terminate abnormally run-time errors
A program may run but produce incorrect results
perhaps using an incorrect formula logical errors
Instructor: Lavi Gupta 09803266066
slide 25: errors
errors
Edit and
save program
Compile program
Execute program and
evaluate results
Instructor: Lavi Gupta 09803266066
slide 26: The Java Programming Language
Program Development
Object-Oriented Programming
Instructor: Lavi Gupta 09803266066
slide 27:
The purpose of writing a program is to solve a
problem
Solving a problem consists of multiple activities:
◦ Understand the problem
◦ Design a solution
◦ Consider alternatives and refne the solution
◦ Implement the solution
◦ T est the solution
These activities are not purely linear – they
overlap and interact
Instructor: Lavi Gupta 09803266066
slide 28:
The key to designing a solution is breaking
it down into manageable pieces
When writing software we design separate
pieces that are responsible for certain parts
of the solution
An object-oriented approach lends itself to
this kind of solution decomposition
We will dissect our solutions into pieces
called objects and classes
Instructor: Lavi Gupta 09803266066
slide 29:
Java is an object-oriented programming language
As the term implies an object is a fundamental
entity in a Java program
Objects can be used efectively to represent real-
world entities
For instance an object might represent a
particular employee in a company
Each employee object handles the processing and
data management related to that employee
Instructor: Lavi Gupta 09803266066
slide 30:
An object has:
◦ state - descriptive characteristics
◦ behaviors - what it can do or what can be done to it
The state of a bank account includes its
account number and its current balance
The behaviors associated with a bank account
include the ability to make deposits and
withdrawals
Note that the behavior of an object might
change its state
Instructor: Lavi Gupta 09803266066
slide 31:
An object is defned by a class
A class is the blueprint of an object
The class uses methods to defne the behaviors
of the object
The class that contains the main method of a
Java program represents the entire program
A class represents a concept and an object
represents the embodiment of that concept
Multiple objects can be created from the same
class
Instructor: Lavi Gupta 09803266066
slide 32: Character Strings
Variables and Assignment
Primitive Data Types
Expressions
Data Conversion
Interactive Programs
Graphics
Applets
Drawing Shapes
Instructor: Lavi Gupta 09803266066
slide 33:
A string of characters can be represented as a
string literal by putting double quotes around
the text:
Examples:
"This is a string literal."
"123 Main Street"
"X"
Every character string is an object in Java
defned by the String class
Every string literal represents a String object
Instructor: Lavi Gupta 09803266066
slide 34:
In the Lincoln program from Chapter 1 we
invoked the println method to print a
character string
The System.out object represents a
destination the monitor screen to which we
can send output
System.out.println "Whatever you are be a good one."
object method
name
information provided to the method
parameters
Instructor: Lavi Gupta 09803266066
slide 35:
The System.out object provides another
service as well
The print method is similar to the
println method except that it does not
advance to the next line
Therefore anything printed after a print
statement will appear on the same line
Instructor: Lavi Gupta 09803266066
slide 36: public class Countdown
//-----------------------------------------------------------------
// Prints two lines of output representing a rocket countdown.
//-----------------------------------------------------------------
public static void main String args
System.out.print "Three... "
System.out.print "T wo... "
System.out.print "One... "
System.out.print "Zero... "
System.out.println "Liftof" // appears on frst output line
System.out.println "Houston we have a problem."
Instructor: Lavi Gupta 09803266066
slide 37:
The string concatenation operator + is
used to append one string to the end of
another
"Peanut butter " + "and jelly"
It can also be used to append a number to a
string
A string literal cannot be broken across two
lines in a program
Instructor: Lavi Gupta 09803266066
slide 38: public class Facts
public static void main String args
// Strings can be concatenated into one long string
System.out.println "We present the following facts for your "
+ "extracurricular edifcation:"
System.out.println
// A string can contain numeric digits
System.out.println "Letters in the Hawaiian alphabet: 12"
// A numeric value can be concatenated to a string
System.out.println "Dialing code for Antarctica: " + 672
System.out.println "Year in which Leonardo da Vinci invented "
+ "the parachute: " + 1515
System.out.println "Speed of ketchup: " + 40 + " km per year"
Instructor: Lavi Gupta 09803266066
slide 39:
The + operator is also used for arithmetic
addition
The function that it performs depends on the
type of the information on which it operates
If both operands are strings or if one is a string
and one is a number it performs string
concatenation
If both operands are numeric it adds them
The + operator is evaluated left to right but
parentheses can be used to force the order
Instructor: Lavi Gupta 09803266066
slide 40: public class Addition
//-----------------------------------------------------------------
// Concatenates and adds two numbers and prints the
results.
//-----------------------------------------------------------------
public static void main String args
System.out.println "24 and 45 concatenated: " + 24 +
45
System.out.println "24 and 45 added: " + 24 + 45
Instructor: Lavi Gupta 09803266066
slide 41:
What if we wanted to print a the quote
character
The following line would confuse the compiler
because it would interpret the second quote as
the end of the string
System.out.println "I said "Hello" to you."
An escape sequence is a series of characters
that represents a special character
An escape sequence begins with a backslash
character \
System.out.println "I said \"Hello\" to you."
Instructor: Lavi Gupta 09803266066
slide 42:
Some Java escape sequences:
Escape Sequence
\b
\t
\n
\r
\"
\
\\
Meaning
backspace
tab
newline
carriage return
double quote
single quote
backslash
Instructor: Lavi Gupta 09803266066
slide 43: public class Roses
//-----------------------------------------------------------------
// Prints a poem of sorts on multiple lines.
//-----------------------------------------------------------------
public static void main String args
System.out.println "Roses are red\n\tViolets are blue\n" +
"Sugar is sweet\n\tBut I have \"commitment issues\"\n\t"
+
"So Id rather just be friends\n\tAt this point in our " +
"relationship."
Instructor: Lavi Gupta 09803266066
slide 44: Character Strings
Variables and Assignment
Primitive Data Types
Expressions
Data Conversion
Interactive Programs
Graphics
Applets
Drawing Shapes
Instructor: Lavi Gupta 09803266066
slide 45:
A variable is a name for a location in memory
A variable must be declared by specifying the
variables name and the type of information
that it will hold
int total
int count temp result
Multiple variables can be created in one declaration
data type
variable name
Instructor: Lavi Gupta 09803266066
slide 46:
A variable can be given an initial value in the
declaration
•
When a variable is referenced in a program its
current value is used
int sum 0
int base 32 max 149
Instructor: Lavi Gupta 09803266066
slide 47: public class PianoKeys
//-----------------------------------------------------------------
// Prints the number of keys on a piano.
//-----------------------------------------------------------------
public static void main String args
int keys 88
System.out.println "A piano has " + keys + " keys."
Instructor: Lavi Gupta 09803266066
slide 48:
An assignment statement changes the value of
a variable
The assignment operator is the sign
total 55
•
The value that was in total is overwritten
•
You can only assign a value to a variable that is
consistent with the variables declared type
•
The expression on the right is evaluated and the
result is stored in the variable on the left
Instructor: Lavi Gupta 09803266066
slide 49: public class Geometry
public static void main String args
int sides 7 // declaration with initialization
System.out.println "A heptagon has " + sides + " sides."
sides 10 // assignment statement
System.out.println "A decagon has " + sides + " sides."
sides 12
System.out.println "A dodecagon has " + sides + " sides."
Instructor: Lavi Gupta 09803266066
slide 50:
A constant is an identifer that is similar to a
variable except that it holds the same value
during its entire existence
As the name implies it is constant not variable
The compiler will issue an error if you try to
change the value of a constant
In Java we use the final modifer to declare a
constant
final int MIN_HEIGHT 69
Instructor: Lavi Gupta 09803266066
slide 51:
Constants are useful for three important reasons
First they give meaning to otherwise unclear
literal values
◦ For example MAX_LOAD means more than the literal 250
Second they facilitate program maintenance
◦ If a constant is used in multiple places its value need
only be updated in one place
Third they formally establish that a value should
not change avoiding inadvertent errors by other
programmers
Instructor: Lavi Gupta 09803266066
slide 52: For online classes contact: 9803266066
Skype: lavigupta18
Email: techlavigmail.com
Instructor: Lavi Gupta 09803266066