Java principles

JavaAdel Al Jaffan

Enas AL Saeek

Reference :

• 1- Thinking in java

• 2- OOP in java (Arabic)

• 3- White Hat lectures (2013-2014)

• 4- Online tutorials ( YouTube – Coursera )

• 5- MORE …. !!!

Object Oriented Programming (O O P)

Object Oriented Programming (O O P)

Let us code !!!

• 1st :

install Java Development Kit “JDK”

• 2nd :

what about IDE : “Netbeans” or “Eclipse” ?

• 3rd :

We must know how to create our first java project ! :D

Classes (only)

• How can I make my

FIRST “CLASS”

Classes (only)

Printing “any thing” !

hi

2

Variables

int a , b, c; // Declares three integers, a, b, and c.

int a = 10, b = 10 ; // Example of initialization

byte B = 22; // initializes a byte type variable B.

double pi = 3.14159; // declares and assigns a value of PI .

char a = 'a'; // the char variable a is initialized with value 'a‘

Variables (casting)

If / else

If / else

Switch case

switch (int value) {

case 1: //

break;

case 2 : //

break;

default : //

break ;

}

Switch case

For loop

While loop

Declaring method ( function/procedure )

• Function :

return type method name ( type variable1, type variable 2 , ..… )

{

// code block

return variable ” same return type”

}

Declaring method ( function/procedure )

• procedure :

void method name ( type variable1, type variable 2 , ..… )

{

// code block

}

Example 1 :

• Make 3 method (add , sub , mult )

Let’s code

Constructors

• 3 TYPES !!!

1) default constructor

We do not write it !!!

2) with non-arguments

s3) with arguments

Objects !!!

• Class_name object_name ; // without initialize … runtime error !

• Class_name object_name = new Class_name ( ) ;

• Class_name object_name = new Class_name ( value ) ;

Example 1 :

Let us code !!!

Example 1 :

Example 1 :

Output :

mewoooo

7

8

Inheritance in java -1

Inheritance in java -2

Inheritance in java -3

Output :

i'm the father

i'm the son

Inheritance in java -4

Overload in java

The conditions for method overloading :

1.) The number of parameters is different for the methods.

2.) The parameter types are different ,

(like changing a parameter that was a float to an int).

Overload in java

How to NOT overload methods :

1. Just changing the return type of the method. If the return type

of the method is the only thing changed, then this will result in

a compiler error.

1. Changing just the name of the method parameters, but not

changing the parameter types. If the name of the method

parameter is the only thing changed then this will also result in

a compiler error.

Overload in java

Example 1 :

Overload in java

Example 2 :

Overload in java

Example 3 :

Overload in java

Example 4 :

Inheritance in java - Override

Example !!!!

Inheritance in java - Override

Output ?!!!!

Exception handling

Try {

//code block

} catch ( Exception e ) {

// code block

} finally {

// code block

}

Example 1 :

- Throw Exception after division operation

Let us code !!!

Good Bye

Any questions ?