1. Introduction to Java Programming

2. Focus of the Course Object-Oriented Software Development
problem solving
program design, implementation, and testing
object-oriented concepts
classes
objects
encapsulation
inheritance
polymorphism

3. Introduction The Java Programming Language Program Development
Object-Oriented Programming

4. Introduction
One characteristic that is constant in the software industry today is the “CHANGE”.
Change is one of the most critical aspects of Software Development and Management.
Since the invention of the Computer, many programming approaches have been tried. Such as modular programming, top-down programming, bottom-up programming and structured programming.
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5. JAVA
A programming language specifies 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 it's popularity has grown quickly since

6. JAVA
Like C, C++ etc. Java is another computer language but with a difference.
Java’s designers have borrowed the best features of many existing language such as C and C++ and added a few new features to form a simple language.
One of the important reason for java’s success is the amazing functionality it adds to the WWW.
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7. Java has two lives, one as a stand-alone computer language for general purpose programming and the other as a supporting language for Internet programming.
The general purpose programs are known as applications and the programs written for internet are known as applets.
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8. Java Program Structure
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

9. Hello.java class abc { public static void main (String[] args)
System.out.println (“hello world"); }

10. Java Program Structure
// comments about the class
public class MyProgram { }
class header
class body
Comments can be placed almost anywhere

11. Java Program Structure
// comments about the class
public class MyProgram { }
// comments about the method
public static void main (String[] args) { }
method header
method body

12. Public:- The keyword ‘public’ is a access
Public:- The keyword ‘public’ is a access specifier that declares the main method as unprotected and therefore making it accessible to all other classes.
Static:- Next appears the keyword ‘static’, which declares this method as one that belongs to the entire class and not a part of any object of class. The main must always be declared as static since the interpreter uses this method before any objects are created.
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13. Void:- This type modifier ‘void’ states that the
Void:- This type modifier ‘void’ states that the main method does not return any values.
All parameters to a method are declared inside a pair of parentheses. Here, String args [ ] declares a parameter named args, which contains an array of objects of the class type String.
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14. Lets see what happens at runtime:-
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15. Comments 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 affect 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 */

16. Identifiers Identifiers are the words a programmer uses in a program
An identifier can be made up of letters, digits, the underscore character ( _ ), and the dollar sign
Identifiers cannot begin with a digit
Java is case sensitive - Total, total, and TOTAL are different identifiers
By convention, programmers use different case styles for different types of identifiers, such as
title case for class names - hello
upper case for constants - MAXIMUM

17. Reserved Words 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

18. Outline The Java Programming Language Program Development
Object-Oriented Programming

19. Program Development
The mechanics of developing a program include several activities
writing the program in a specific programming language (such as Java)
translating the program into a form that the computer can execute
investigating and fixing various types of errors that can occur
Software tools can be used to help with all parts of this process

20. Programming Languages
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 specific target language
Often, that target language is the machine language for a particular CPU type
The Java approach is somewhat different

21. Java Translation
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

22. Java Translation Java source code Java bytecode Java compiler Bytecode
interpreter
Bytecode
compiler
Machine
code

23. Development Environments
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 differ, the basic compilation and execution process is essentially the same

24. Syntax and Semantics
The syntax rules of a language define how we can put together symbols, reserved words, and identifiers to make a valid program
The semantics of a program statement define 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

25. Errors A program can have three types of errors
The compiler will find 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)

26. Basic Program Development
Edit and
save program
errors
errors
Compile program
Execute program and
evaluate results

27. Outline The Java Programming Language Program Development
Object-Oriented Programming

28. Problem Solving 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 refine the solution
Implement the solution
Test the solution
These activities are not purely linear – they overlap and interact

29. Problem Solving
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

30. Object-Oriented Programming
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 effectively 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

31. Objects
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

32. Classes An object is defined by a class
A class is the blueprint of an object
The class uses methods to define 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

33. Data and Expressions Character Strings Variables and Assignment
Primitive Data Types
Expressions
OOP

34. Character Strings
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, defined by the String class
Every string literal represents a String object

35. System.out.println (“hello world");
The println Method
In the hello program studied earlier, 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 (“hello world");
information provided to the method
(parameters)
method
name
object

36. The print Method
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

37. Countdown.java 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 ("Two... ");
System.out.print ("One... ");
System.out.print ("Zero... ");
System.out.println ("Liftoff!"); // appears on first output line
System.out.println ("Houston, we have a problem."); }

38. "Peanut butter " + "and jelly"
String Concatenation
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

39. Facts.java 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 edification:");
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: " );
System.out.println ("Speed of ketchup: " " km per year"); }

40. String Concatenation
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

41. Addition.java 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: " );
System.out.println ("24 and 45 added: " + ( )); }

42. Escape Sequences 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.");

43. Escape Sequences Some Java escape sequences: Escape Sequence \b \t \n\r
\" \' \\
Meaning
backspace
tab
newline
carriage return
double quote
single quote
backslash

44. Roses.java 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 I'd rather just be friends\n\tAt this point in our " +
"relationship."); }

45. Multiple variables can be created in one declaration
A variable is a name for a location in memory
A variable must be declared by specifying the variable's name and the type of information that it will hold
data type
variable name
int total;
int count, temp, result;
Multiple variables can be created in one declaration

46. Variable Initialization
A variable can be given an initial value in the declaration
int sum = 0;
int base = 32, max = 149;
When a variable is referenced in a program, its current value is used

47. PianoKeys.java 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."); }

48. Assignment An assignment statement changes the value of a variable
The assignment operator is the = sign
total = 55;
The expression on the right is evaluated and the result is stored in the variable on the left
The value that was in total is overwritten
You can only assign a value to a variable that is consistent with the variable's declared type

49. Geometry.java 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."); }

50. final int MIN_HEIGHT = 69;
Constants
A constant is an identifier 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 modifier to declare a constant
final int MIN_HEIGHT = 69;

51. Constants 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
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52. Oop Java is an object oriented programming language.
Its main concepts are:-
Inheritance
Polymorphism
Exception handling
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53. 1. Inheritance
Reusability is aspect of OOP paradigm. It is always nice if we could reuse something that already exist rather than creating the same all over again. Java support this concept. This is basically done by creating new classes, reusing the properties existing on.
Inheritance can be defined as the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.
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54. Types Single Inheritance Multilevel Inheritance
Hierarchical Inheritance
Multiple Inheritance
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55. Extends & Implements
When we talk about inheritance, the most commonly used keyword would be extends and implements. These words would determine whether one object IS-A type of another. By using these keywords we can make one object acquire the properties of another object.
We inherit class from existing class throw ‘extends’ keyword but java does not directly extends more than one class. However this concept is implements using secondary inheritance path in the form of ‘interface’ using implements keyword.
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57. Extends Let us see how the extends keyword is used to
achieve inheritance.
Class vehicle {
………….. }
class car extends vehicle
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58. Implements Interface color { …………. } Class Car implements color …………..
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59. Example:-
Class vehicle { String vehiceType; } interface Colour String car_colour;
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60. Public class car extends vehicle implements colour { String modelType;
Public void showdetail()
vehicaltype=“car”;
modeltype=“sports”;
car_colour=“red”;
System.out.println(modelType+vehicleType+car_colour); }
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61. public static void main(String[] args) { Car car=new car(); Car
public static void main(String[] args) { Car car=new car(); Car.showdetail(); }
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62. Output:- Sports car red
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63. 2.Polymorphism:-
Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.
Any Java object that can pass more than one IS-A test is considered to be polymorphic. In Java, all Java objects are polymorphic since any object will pass the IS-A test for their own type and for the class Object.
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64. Example:-
Class game { Public void type() System.out.println(“Indoor & outdoor”); } Class cricket extends game System.out.println(“outdoor game”)}
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65. Public static void main(String[] args) { Game gm= new Game(); Cricket ck= new cricket(); gm.type(); ck.type(); gm=ck; }
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66. Output:- Indoor & outdoor Outdoor game
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67. 3. Exception handling:-
An exception is a problem that arises during the execution of a program. An exception can occur for many different reasons, including the following:-
=> A user has entered invalid data.
=> A file that needs to be opened cannot be found.
=> A network connection has been lost in the middle of
communications or the JVM has run out of memory.
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68. To understand how exception handling works in Java, you need to understand the three categories of exceptions:
Checked exceptions: A checked exception is an exception that is typically a user error or a problem that cannot be foreseen by the programmer. For example, if a file is to be opened, but the file cannot be found, an exception occurs. These exceptions cannot simply be ignored at the time of compilation.
Runtime exceptions: A runtime exception is an exception that occurs that probably could have been avoided by the programmer. As opposed to checked exceptions, runtime exceptions are ignored at the time of compilation.
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69. Errors: These are not exceptions at all, but problems that arise beyond the control of the user or the programmer. Errors are typically ignored in your code because you can rarely do anything about an error. For example, if a stack overflow occurs, an error will arise. They are also ignored at the time of compilation.
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70. Exception Hierarchy:-
The exception class is a subclass of the Throwable class. Other than the exception class there is another subclass called Error which is derived from the Throwable class.
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71. Note:- some exceptions cant be handeld, they leads to unexpected program termination. These type of exceptions are called Uncaught exceptions. For example:- Class uncaught exception { Public static void main(String[] args) Int a=0; Int b=7/a; }
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72. Output:-
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