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Introduction
The Basics
Programming in Java
Further Reading
Introduction to Java
Panagiotis Louridas [email protected]
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Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Outline
1
Introduction
A Bit of History
The Java Runtime Environment
Java Programs
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Outline
1
2
Introduction
A Bit of History
The Java Runtime Environment
Java Programs
The Basics
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Outline
1
2
3
Introduction
A Bit of History
The Java Runtime Environment
Java Programs
The Basics
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Programming in Java
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Outline
1
2
3
4
Introduction
A Bit of History
The Java Runtime Environment
Java Programs
The Basics
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Programming in Java
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Further Reading
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
A Bit of History
The Java Runtime Environment
Java Programs
A Bit of History
Bill Joy, 1990: Sun Aspen Smallworks
James Gosling, 1992: FirstPerson. Work on “C++ minus
minus”
Demise of Apple Newton: efforts shift to interactive TV (ITV)
Oak: a language for ITV
1993: Oak becomes Java
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
A Bit of History
The Java Runtime Environment
Java Programs
The Java Runtime Environment
Learning Java, 3rd Edition, O’Reilly, 2005
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
A Bit of History
The Java Runtime Environment
Java Programs
Types of Java Programs
Applets
j2me
Desktop applications
Server applications
Network applications
...
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Java Compared to Other Languages
Learning Java, 3rd Edition, O’Reilly, 2005
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Java Principles
Simplify
Object Orientation
Type safety
Runtime information
Error handling
Threads
Collections
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
What is an Object
An object is an entity containing data and code, or state and
behaviour
The Java Tutorial, 4th Edition, Prentice Hall PTR, 2006
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
A class example
class Bicycle {
int cadence = 0;
int speed = 0;
int gear = 1;
v o i d c h a n g e C a d e n c e ( i n t newValue ) {
c a d e n c e = newValue ;
}
v o i d c h a n g e G e a r ( i n t newValue ) {
g e a r = newValue ;
}
v o i d speedUp ( i n t i n c r e m e n t ) {
speed = speed + increment ;
}
void applyBrakes ( i n t decrement ) {
speed = speed − decrement ;
}
void p r i n t S t a t e s ( ) {
System . o u t . p r i n t l n ( ” c a d e n c e : ”+c a d e n c e+” s p e e d : ”+s p e e d+” g e a r : ”+g e a r ) ;
}
}
The Java Tutorial, 4th Edition, Prentice Hall PTR, 2006
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
A Bicycle Demo
c l a s s Bi cy c leDe mo {
p u b l i c s t a t i c v o i d main ( S t r i n g [ ] a r g s ) {
// C r e a t e two d i f f e r e n t B i c y c l e o b j e c t s
B i c y c l e b i k e 1 = new B i c y c l e ( ) ;
B i c y c l e b i k e 2 = new B i c y c l e ( ) ;
// I n v o k e methods on t h o s e o b j e c t s
b i k e 1 . c h a n g e C ad e n c e ( 5 0 ) ;
b i k e 1 . speedUp ( 1 0 ) ;
bike1 . changeGear ( 2 ) ;
bike1 . printStates ( ) ;
b i k e 2 . c h a n g e C ad e n c e ( 5 0 ) ;
b i k e 2 . speedUp ( 1 0 ) ;
bike2 . changeGear ( 2 ) ;
b i k e 2 . c h a n g e C ad e n c e ( 4 0 ) ;
b i k e 2 . speedUp ( 1 0 ) ;
bike2 . changeGear ( 3 ) ;
bike2 . printStates ( ) ;
}
}
The Java Tutorial, 4th Edition, Prentice Hall PTR, 2006
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Inheritance
The Java Tutorial, 4th Edition, Prentice Hall PTR, 2006
c l a s s M o u n t a i n B i k e extends B i c y c l e {
// new f i e l d s and methods d e f i n i n g a mountain b i k e
// would go h e r e
}
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Java Compared to Other Languages
Java Principles
Object Orientation in a Nutshell
Interfaces
Interfaces are like classes, but without implementation
interface Driveable {
boolean s t a r t E n g i n e ( ) ;
void stopEngine ( ) ;
f l o a t a c c e l e r a t e ( f l o a t acc ) ;
boolean t u r n ( D i r e c t i o n d i r ) ;
}
c l a s s A u t o m o b i l e implements D r i v e a b l e {
...
p u b l i c boolean s t a r t E n g i n e ( ) {
i f ( notTooCold )
engineRunning = true ;
...
}
public void stopEngine ( ) {
engineRunning = f a l s e ;
}
public f l o a t a c c e l e r a t e ( f l o a t acc ) {
...
}
p u b l i c boolean t u r n ( D i r e c t i o n d i r ) {
...
}
...
}
Learning Java, 3rd Edition, O’Reilly, 2005
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Hello World
public class HelloJava {
p u b l i c s t a t i c v o i d main ( S t r i n g [ ] a r g s ) {
System . o u t . p r i n t l n ( ” H e l l o , J a v a ! ” ) ;
}
}
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Graphical Hello World
import j a v a x . s w i n g . ∗ ;
public class HelloJavaSwing {
p u b l i c s t a t i c v o i d main ( S t r i n g [ ] a r g s ) {
JFrame f r a m e = new JFrame ( ” H e l l o , J a v a ! ” ) ;
J L a b e l l a b e l = new J L a b e l ( ” H e l l o , J a v a ! ” ,
J L a b e l . CENTER ) ;
f r a m e . add ( l a b e l ) ;
frame . s e t S i z e (300 , 3 0 0 ) ;
frame . s e t V i s i b l e ( true ) ;
}
}
Learning Java, 3rd Edition, O’Reilly, 2005
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Graphical Hello World with Interaction
The main class
import j a v a . awt . ∗ ;
import j a v a . awt . e v e n t . ∗ ;
import j a v a x . s w i n g . ∗ ;
public class HelloJava2 {
p u b l i c s t a t i c v o i d main ( S t r i n g [ ] a r g s ) {
JFrame f r a m e = new JFrame ( ” H e l l o J a v a 2 ” ) ;
frame . getContentPane ( )
. add ( new HelloComponent ( ” H e l l o , J a v a ! ” ) ) ;
f r a m e . s e t D e f a u l t C l o s e O p e r a t i o n ( JFrame . EXIT ON CLOSE ) ;
frame . s e t S i z e (300 , 3 0 0 ) ;
frame . s e t V i s i b l e ( true ) ;
}
}
Learning Java, 3rd Edition, O’Reilly, 2005
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Graphical Hello World with Interaction
The HelloComponent class
c l a s s HelloComponent extends JComponent
implements M o u s e M o t i o n L i s t e n e r {
S t r i n g theMessage ;
i n t messageX = 1 2 5 , messageY = 9 5 ; // C o o r d i n a t e s o f t h e message
p u b l i c HelloComponent ( S t r i n g message ) {
t h e M e s s a g e = message ;
addMouseMotionListener ( this ) ;
}
p u b l i c v o i d p ain t Co mp on en t ( G r a p h i c s g ) {
g . d r a w S t r i n g ( theMessage , messageX , messageY ) ;
}
p u b l i c v o i d mouseDragged ( MouseEvent e ) {
// Save t h e mouse c o o r d i n a t e s and p a i n t t h e message .
messageX = e . getX ( ) ;
messageY = e . getY ( ) ;
repaint ();
}
p u b l i c v o i d mouseMoved ( MouseEvent e ) { }
}
Learning Java, 3rd Edition, O’Reilly, 2005
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Sort Arguments
import j a v a . u t i l . ∗ ;
p u b l i c c l a s s FindDups {
p u b l i c s t a t i c v o i d main ( S t r i n g [ ] a r g s ) {
Set<S t r i n g > s = new HashSet<S t r i n g > ( ) ;
for ( String a : args )
i f ( ! s . add ( a ) )
System . o u t . p r i n t l n ( ” D u p l i c a t e d e t e c t e d : ” + a ) ;
System . o u t . p r i n t l n ( s . s i z e ( ) +
” d i s t i n c t words : ” + s ) ;
}
}
The Java Tutorial, 4th Edition, Prentice Hall PTR, 2006
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Hello World
Graphical Hello World
Graphical Hello World with Interaction
Collections
Shuffle Arguments
import j a v a . u t i l . ∗ ;
public class Shuffle {
p u b l i c s t a t i c v o i d main ( S t r i n g [ ] a r g s ) {
L i s t <S t r i n g > l i s t = A r r a y s . a s L i s t ( a r g s ) ;
Collections . shuffle ( l i s t );
System . o u t . p r i n t l n ( l i s t ) ;
}
}
The Java Tutorial, 4th Edition, Prentice Hall PTR, 2006
Louridas
Introduction to Java
Introduction
The Basics
Programming in Java
Further Reading
Further Reading
S. Zakhour, S. Hommel, J. Royal, I. Rabinovitch, T. Risser, M.
Hoeber, The Java Tutorial: A Short Course on the Basics, 4th
edition, Prentice Hall PTR, 2006. Online version at: http:
//java.sun.com/docs/books/tutorial/index.html
J. Knudsen, P. Niemeyer, Learning Java, 3rd edition, O’ Reilly,
2005.
B. Eckel, Thinking in Java, 4th edition, Prentice Hall PTR,
2006.
Louridas
Introduction to Java