1. JAVA An Introduction to Java OOP Basics
Mudassir Hasan

2. Data Types & Operators
Data Types: byte, short, int, long, float, double, long , boolean, char
Operators:
- Arithmetic: +,-,*,/, % ( modulus-remainder )
- Relational: <, >, <=, >=, ==, !=
- Logical: &&, ||, !

3. Strings public class LearnJava
{ public static void main( String [] args ) { String fun = “Java is fun”;
System.out.println(fun); } }

4. Strings (cont’d.) Date columbusDay = new Date(10, 12, 2009);
System.out.println(“Columbus day was on “ +
columbusDay.getDay() );
Columbus day was on 12
Stores values for columbusDay.
int age = 20; // String Concatenation String youth = "He is " + age + " years old."; System.out.println(youth);
He is 20 years old.

5. Modifiers Access Modifiers:
Public – access methods of the same class and of other classes
Private – access methods of the same class only
Protected – access methods in the same class and also in subclasses

6. Constructors Initializes the fields of the new object
It is called when an object is instantiated using the new keyword
For example: Auto suv = new Auto( );

7. Constructors Default Constructor public class Auto {
private int drivenMiles;
private int modelYear;
public Auto ( ) // same name as the class
// no parameters passed, auto initialized drivenMiles to 0.
modelYear = 2009; }

8. Constructors (cont’d.)
Overloaded Constructors
public Auto(int adriven Miles, int amodelYear )
// passes parameter, allows user to set their own values

9. Class Methods Accessor Methods, also called get Methods Get radius
public int getRadius( ) { return radius; }

10. Class Methods Mutator Methods, also called set Methods
Allows the user to set its own values in the client class
public Class
public void setRadius( int newRadius ) { radius = newRadius; }
Client Class Circle circ = new Circle( 4 );

11. Arrays public class ArrayElements {
public static void main(String [] args)
double cells = new double [3]
cells[0] = 1;
cells[1] = 2;
cells[2] = 3; }
First index is 0.
Last index is [array.length – 1]

12. Swapping Array int temp = array[2]; array[2] = array[4];
array[4] = temp;
Value 23 45 7 33 78
Index 1 2 3 4 5

13. Class
public class Circle { private int point; private int radius; public Circle( int newPoint, int newRadius ) { point = newPoint; radius = newRadius; } public int getLocation() { return point; } public void setLocation( int newPoint) { point = newPoint; }

14. Class (cont’d.)
public int getRadius() { return radius; } public void setRadius( int newRadius ) { radius = newRadius; } public double getPerimeter() { return 2 * Math.PI * radius; } public double getArea() { return Math.PI * radius * radius; } public String toString() { return "The point is " + point "\nThe radius is " + radius "\nPerimeter of the circle is " + getPerimeter() "\nArea of the circle is " + getArea();

15. Client Class
public class ClientCircle { public static void main( String [] args ) { Circle circ = new Circle( 4, 5 ); System.out.println( circ.toString() ); } } The point is 4 The radius is 5 Perimeter of the circle is Area of the circle is

16. Bibliography
Anderson, Julie and Franceschi, Herve. Java Illuminated.