java

1
???? ?????? ? java

• ????? ????? ????? ????? 4
• ?????

2
????? ??? ???

• ???? ?? ????? 4 ?'
• ???? ?????? ?????, ???? ????, Object.
• ?????
• ????, ?????,
• ?????? ? polymorphism
• ????? ??????? ???? ???.
• ???? ????????? ??????.

3
????? - ????????

• ??? ????????? ??????? ?? ????? ????? ?????.
• ?????? ??????? ??? ???????.
• ?????? ???? ????? ??? ??????.
• ????? ??? (???? ???? ?? windows).
• ???? ???? ?? ????.

4
???? ??????? ?????

• ????? ??????
• ????, ?????, ?????, ??????.
• ????? ?????? ??????, toString().
• ???? ?? ????????
• ????? ????? ?? ??????.
• ???? ????? ????? ?? ?? ?????? ??? (?????)
• ????? ??????, ???? ????????.

5
???? ???? ????????

• ?????? ????? ??? ????? ?? ????????
  StudentContainer
• ??? ????? ???? ?? ?????????
• ?????, ????, ??????

6
???? ???? ???????? 1
public class StudentContainer1 // data
members public static final int
INIT_SIZE10 // the first (init) size. public
static final int RESCALE10 // the re-scale
factor private int _sp0 private Student
_students / Constructors creates a empty
set / public StudentContainer1() _sp0 _
students new StudentINIT_SIZE
7
???? ???? ???????? 1
/ this method returns a list of all the
Students / public String toString() String
ans "StudentContainer1 "size()"\n" for(
int i0 iltthis.size()ii1) ans (i1)")
"at(i)"\n" return ans
8
???? ???? ???????? 1
9
???? ???? ???????? 3

• ?????? ??? ????? ????
• ????? ?????? ?????.
• ???? ??? ??? ???? ?"? ?????????.
• class Student //
• public boolean equals(Student other)
• return other!null this.getID()
  other.getID()
• public boolean smaller(Student other)
• return othernull this.getID() lt
  other.getID()

10
???? ???? ???????? 3
public class StudentContainer3 // data
members StudentContainer1 _sc public
StudentContainer3() _sc new
StudentContainer1() public Student
search(Student s) return at(find(s))
public Student search(long id) return
search(new Student(id,"Dammi"))
11
???? ???? ???????? 3
public boolean member(Student s) return
this.search(s)!null / add a Student to
this set! / public void add (Student
p) if(p!null !this.member(p))
_sc.add(p) sort() else
System.out.println(" ERR can not add "p" to
the set! ")
12
????? - ??????? ?? ???????

• ??? ?????? ???? ????? ??? ??????? ???? ?????.
• ??? ?????? ??? ??? ?????? ????? ???? ??? ?????
  ?? ??????.
• ??? ???? ?????? ???? ???? ?? ?????????

13
??????? ?? ?????? - ?????

• ????? ???? ???? ?? ???? (???? ???? ?????)
• ????? ??? ?????? ???? ????? (??? ?????)
• ????? ?? ?????? ???? ????? 4

14
??????? ?? ?????? - ?????

• ???? ?????? ????? ????????? ??????? ?????
• ????? ????? ?????.
• Shape sp new Shape4
• sp0 new Rect()
• sp1 new Circle(new Point(1,1),4)
• sp2 new Shape()
• ???? ????? ?? ?????? ????? ????, ??????,

15
??????? ?? ?????? - ?????

• ?????? Shape, ???? ????? ??? ?????
• ?????
• ???, ????, toString()
• ??? ?????, ????? ???..
• ????? Constructor
• ???? ??? (???? ???? ?? int)

16
??????? ?? ?????? - ?????
public class Shape private int
_color public Shape(int c) this._color
c public void setColor(int c)this._color
c public int getColor() return
_color public double area() ??? return 1
17
????? ????

• ?? ????? ????? ???? ???? ?????? ??? color
• ???? ????? ??????? ??????? ???? ???? ???????
  ??????? - area().
• ??? ????? ???? ?? ?????? ???? ?????? ?????
  (????? ????? ?????? extends ?????? ??????).

18
?????? Circle ????? ? Shape

• ????? ?????
• ???, toString
• ??? ???? ???? ?????

class Circle extends Shape public double
area() // over riding!! return
Math.PI_radiud_radius public String
toString() return Circle
cen_center rad _darius // class
Circle
19
????? ????

• ???? ???? ?? ????!! ??? ???? ?????? ?? ???? ????
  ????? ???? ????? ????? ?? ????? ???? ?????!
• ? java ????? ????? ???? ?????? ??? ????!.
• ?????? ???? ????? ???? super (????? ? this)

20
?????? Circle ????? ? Shape
??? ????? ??? ???? ???? ?? ???? ???? ?? ?????
????
class Circle extends Shape public
Circle(point p, double r, int color)
super(color) // must be the first line!
// class Circle

• ???? ?? ????? ????? ???? ?????
• ??????? ????? ????? ???? ???!!

21
????? ?????? ?????? ??????

• Java ????? (???? ????) ?? ??????? ????? ????? ???
  ????.
• ???? ????? ???? ?? ???????
• ???? ??? ????? ????? ?????? (????? ????????)
• ?? ?? ???? ???? ??? ?????? ???? ???? (??? ????).
• ??????? ??? ???? poly-morphism ?????
• ????? ?? ???? ?? ????? ????? ?????? ?? ???? ?? ??
  ???? ????? ?????? ???? ?? ???????? ??????!!

22
????? ?????? ?????? ??????

• ??? ?? ???????
• ???? ?? ??? ?? ?????? ????? (???? ???? ????? ???
  ??????)
• ?????? ????? ?????? ????????, ?????? ???? ???????
  ?????? (?????? ??? \ ????? ????? ????).

23
????? ??????? ???? ???

• ??? ???? ???? ??? ?????? ???? ??? ??????? ??
  ???? ????? ?? ?????? (????? ?? ??????? ???????).
• ????? ???? ?????? instanceof, ?????
• if(arri instanceof Circle)
• instanceof ??????? ?????? ????? ??????? (?????)
  ?????? (?????) ????? ??? ?? ???????? ????
  ?????? ?? ??????.
• ???? ?? ????? ??? ????? ???? ???
• If(arri instanceof Shape)

24
????? ??????? ???? ???

• ????????? ???? ???? ?? ???? ???? ?? ????? ??????
  ???? ?? ????? ????? ??? ?????? ?????? ?? ????
  ???? ????, ?????? ???????.
• ?????
• if(arri instanceof Circle) // run time.
• Circle c (Circle)arri // compile time.
• double rad c.radius() // return this radius
• double rad2 arri.radius() // Error (compile
  time)
• //.

25
????? ??????? ???? ??? - Object

• ?? ???????? ??? ??????? ?????? ? Object
• ???? ????? ???? Object arr new Object5
• ???? ?????? ?? ????? ?? ????? (?????? ??????? ..)
• ? Object ???? ????? ???? toString()
• ????? ?????? ?? ?????? Object (java api)
• ?? ??????? ???? ?????? Object!

26
???? ???? ???? - Collection

• ??? ?????
• ?????? ?? ???? ????
• ????? ?????.
• ?????, ????? ??????, ????? ????????.
• ???? ??????, ???? ?????.
• ?????? ????.
• ??????.
• ????? ????? ????

27
???? ???? ???? - Collection

• ?????? ?????
• ???? ????? ????? ????????? ???????? ?????.
• ???? ???? ?? ????? ????? ????? ????, ??????.
• ???? ?????? Object
• ????? ???? ????? ?? ????? ???? ? java
• ????? ???? ???? ????? ??? ?? ???????.

28
???? ???? ???? - Collection

• ????? ?????? Object ??? ?????? ???? ????
  (vector)
• ?????
• ?????
• ?????
• ????
• ????? ????? ???????, ????????? \ ????

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???? ???? ???? - Collection
public class MyVector // data members
public static final int INIT_SIZE10,
RESCALE10 private int _sp0 private
Object _objs / Constructors creates a
empty set / public MyVector() _sp0 _obj
s new ObjectINIT_SIZE
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???? ???? ???? - Collection
public int size() return _sp public void add
(Object p) if (p ! null) if(_sp_objs.len
gth) rescale(RESCALE) _objs_sp p //
reference copy semantic. _sp1 public
Object at(int p) return _objsp // ?????!!
31
???? ???? ???? - Collection
/ return true if obj equals to one of the
vector elements/ public boolean member(Object
obj) boolean ans false for(int
i0obj!null !ans iltthis.size()ii1)
if(obj.equals(at(i))) ans true return
ans
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???? ???? ???? - Collection
class StudentContainer4 extends MyVector public
StudentContainer4() super() public void add
(Object p) // over rides!!! if(p instanceof
Student !member(p)) super.add(p) el
se System.out.println(" ERR )
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???? ???? ???? - Collection

• ????? ? at ?? ???? ????????? StudentContainer4
  ????? ???????
• ?? ????? ?????? ?????? ????????? ???? ??????
  ???? ???? (down cast), ?????? (??? class13.java )
• SOP( ( (Student)sc1.at(0) ).getID() )
• ???? ?? ??????? ??? ??? ???? ???? ?????????.

34
?????? ??? ???? ????????

• ???? ????? ?? ??????? ?????? ?????!
• ???? ??????? ???? (?? ???????), ?????? ????????
  ????? ????? (????? ?????) ??? ????? ????? ???
  ????? ???? ?? ????????, ????? ?? ???? this.
• ??????? ????? ???? ?????? ?? ?? ??????? (???? ???
  ???? ????? ?? this).

35
???? ????????? ??????

• ???? ????? ????? ?????? ?? ??????? (????? ??
  this).
• ???? ?????? ????? ??????? ???? ?????? ???? ???.
• ???? ??? ??? ???? ??? ???????? ????? ??????
  ???????
• ???? ???? ???? ????? ?????? ??? ??????? ??? ????
  ???? ???? ???? ?????? (?? ??????? ???? ????
  ?????? ????).
• ??????? ????? ???? ????? ?? this ???? ?????
  ????? ?? ?? ???? ???? ?? ??????.

36
???? ????????? ?????? - ?????

• public class Shape
• private static int _counter 0
• private int _color
• public Shape(int c)
• this._color c
• _counter
• public static int instances() return _counter

37
?? ????? ????

• ?????
• ???????? ?????? ???????.
• ?????? ??????, (???? ???? ?? ????).
• ?????? ?????? ?? ????? polymorohism
• ????? ??????? ???? ???, ???? (casting).
• ????? ???? ???? ???? Object
• ???? ????????? ??????.