lecture1 intro java part1

7/23/2019 Lecture1 Intro Java Part1

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1

Advanced ProgrammingMethodsLecture 1


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2

Lectures OverviewObject-oriented languages:

- Java

- C

!e"t # or $ lectures:

- Lecture 1 and 1%2 Lecture 2: Java basics

- 1%2Lecture 2 and Lecture #: C basics


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#

Java &e'erences

(ruce )c*el+ Thinking in Java

,he Java ,utorials+ 21#.htt/s:%%docs.oracle.com%javase%tutorial%

Java 0 AP+ 21.htt/:%%docs.oracle.com%javase%0%docs%a/i%

J. (loch. )''ective Java+ 2nd )dition. Addison 3esle4+20.htt/s:%%cebul*o.com%Programming-&esources%)''ective52Java52-522nd52)dition./d'
https://docs.oracle.com/javase/tutorial/http://docs.oracle.com/javase/8/docs/api/http://docs.oracle.com/javase/8/docs/api/https://docs.oracle.com/javase/tutorial/


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Java ,echnolog4


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Java language

6ariables7eclaration:

type name_var1[=expr1][, name_var2[=expr2]];

Primitive 7ata ,4/es

,4/e !r. b4te 6alues 7e'ault value

boolean - true+ 'alse 'alse

b4te 1 -120 8 912 ;b4te


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Java Language

)"am/les:boolean gasit=true;

int numar=34, suma;

float eroare=04!;

"#ar litera=$"%;

litera=$f%;

litera=litera&1;


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Java Comments

1.'' entire line

2.'( multiple

lines ('

#.'(( use) by )o"umentation *ava)o" tool

multiple

lines('

Obs: Comments canot be nested into strings.

'( '(

(' (' +- ./

'(

''

''

(' .//


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Java Constants

final type name [=value];

)"am/les:

a< final int =100;

b< final int ;

=100;8

=1!0; ''error


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Arra4

Arra4 with one dimension

type[] name;

type name[];

Arra4 allocation:

array_name=ne type[)im]; ''memory allo"ation

''in)ex 0 )im1

Accessing an arra4 element: arra4Bname[in)ex]

)"am/les:

float[] ve";

ve"=ne float[10];

int[] sir=ne int[3];

float tmp[];

tmp=ve"; ''ve" an) tmp refer to t#e same array


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One dimension Arra4

Built-in length: returns the arra4 dimension.int[] sir=ne int[!];

int lung_sir=sirlengt#; ''lung=!;

sir[0]=sirlengt#;

sirlengt#=2; ''error

int[] y;

int lung_y=ylengt#; ''error, y as not "reate)

)ouble[] t=ne )ouble[0];

int lung_t=tlengt#; ''lung_t=0;

t[0]=23 ''error5 in)ex out of boun)s

t#e s#ort"ut syntax to "reate an) initiali6e an array5

int[] )x=71,0, 18;


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&ectangular multidimensional arra4

7eclaration:type name[][][][];

type[][][][] name;

Creation:

name=ne type[)im1][)im2][)imn];

Accessing an element:

name[in)ex1][in)ex2][in)exn];

)"am/les:

int[][] a;a=ne int[!][!];

a[0][0]=2;

int x=a[2][2]; ''x=9


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!on-&ectangular Multidimensional Arra4

)"am/les:int[][] a=ne int[3][];

for:int i=0;i3;i&&ab"?;

s=s&?123?; ''"on"atenating strings

Atring t=s;''t=>ab"123?

t&=>12?; ''t=9, s=9

Dtring content can not be changed: t[0]=$%;

"#ar "=t"#art:0


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O/eratorsarihtmetic: &, , (, ', F

relational: E, E=, , =, /=, ==

increment%decrement:&&,

prefix5 int a=2;

int b=&&a; ''a=2, b=2

postfix5 int a=2;

int b=a&&; ''a=3, b=2

assignment: =, &=, =, (=, '=

conditional:GG, HH, /

bitise5 shi'tEE, , EEE,

- conditional G, H, I :not


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O/erator /recedence

O/erators Precedence ;higher /recedence on to/+ the same /recedence on the same lineab"MZ?

7estructor: n Java there is no an4 destructor. ,he garbage collector deallocates the memor4 .


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Objects as Parameters

Objects can be 'ormal /arameters 'or the methods

A method can return an object or an arra4 o' objects.

publi" "lass Cational7

private int numarator, numitor;

''Donstru"tors

publi" voi) a)una:Cational r


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Passing arguments

Primitive t4/e arguments ; boolean+ int+ b4te+ long+ double< are /assed b4 value. ,heir

values are co/ied on the stac*. Arguments o' re'erence t4/e are /assed b4 value. A re'erence to them is co/ied on the

stac*+ but their content ;'ields 'or objects+ locations 'or arra4< can be modi'ied i' themethod has the rights to accces them.

1. ,here is not an4 wa4 to change the /assing mode; li*e in C99


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Passing arguments

"lass S7

int val; publi" S:int x


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Passing arguments

"lass S7

int val; publi" S:int x


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Arra4 o' objects )ach arra4 element must be allocated and intialied.

publi" "lass -ablouribie"te 7

stati" voi) generea6a:int nrMlem, Domplex[] t


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Arra4 o' objects stati" Domplex suma:Domplex[] t


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,he methods toDtring and eEuals

publi" "lass Domplex7 private )ouble real, imag;

publi" Domplex:)ouble re, )ouble im


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Dtatic methods

Are declared using the *e4word stati"

-#ey are s#are) by all "lass instan"es

publi" "lass Domplex7

private )ouble real, imag;

publi" Domplex:)ouble re, )ouble im


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Dtatic methods

,he4 are called using the class name:

Domplex a,b;'' initiali6ation a an) b

Domplex "=Domplexa)una:a, b


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Dtatic 'ields

publi" "lass +atural7private long val;

publi" stati" long =232 ''2JN31

''

8

publi" "lass Xro)us 7

private stati" long "ounter;

private final long i)="ounter&&;

publi" Atring toAtring:


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Dtatic 'ields

nitialiation:

At declaration site:publi" stati" long =2000;

n a s/ecial intialiation bloc*

publi" "lass +atural 7

publi" stati" long ;

stati" 7

=2000;

8

' a static 'ield is not intialied+ it will ta*e the de'ault value o' its t4/e:

private stati" long "ounter; ''0

lecture1 intro java part1

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