java

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

• ????? ????? ????? ????? 3
• ??????, ????, ???? ??????

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

• ????? ?? ?????? ?????? PointContainer
• ?????? ????? ????, ????, ???? ????
• ???? ????, Object
• ???? ??????
• ???? ????????? ??????.

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

• ?????? ?????, ??????? ?????, ??????.
• ????? ?? ?"??" ??"???".
• ???? ?????? ??????????? ?????? ???? ????.
• ???? ???? (vector)
• ?????????? ?? ???? ?????, ????...

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

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

public class Point private double _x, _y
public Point (double x1, double y1)
_x x1 _y y1 public double
distance(Point p) double dx
x()-p.x(), dy _y-p._y // x() , _x
return Math.sqrt(dxdx dydy)
5
????? ????????? ??????? this

• ??? ????? ???? ????? ????????? ????.
• this ????? ?? ??? ???? ?????? ?? ?????.
• Point pnew Point(5,6)
• Circle cnew Circle(p,4)
• Circle c2

6
????? ????? ??????

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

public class Student private String _name
private long _id private int _grades
public Student(long id, String name) _name
new String(name) // copy. _id id
_grades new int5 // .
7
????? ????? ??????

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

public class Student private int
_grades public void updateGrade(int ind, int
grade) ... public int gradeAt(int ind)
public int finalGrade()
8
????? ????? ????? - ????

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

9
????? ?????? StudentContainer
class TestStudent public static void
main(String a) Student s1 new
Student(123456789, Dan) /// Student s10
new Student(55555555, Noam) StudentContain
er st new StudentContainer() st.add(s1)
st.add(s10) S.o.p(st.search(555555555))
10
???? ???? ???????? 1

• ?????? ????? ??? ????? ?? ?????? ShapeContainer
• ??? ????? ???? ?? ?????????
• ?????, ????, ??????

11
???? ???? ???????? 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
12
???? ???? ???????? 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
13
???? ???? ???????? 1
14
???? ???? ???????? 2

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

15
???? ???? ???????? 2
16
???? ???? ???????? 2
public class StudentContainer2 // data
members StudentContainer1 _sc /
Constructors creates a empty set / public
StudentContainer2() _sc new
StudentContainer1() / returns the actual
amount of Student in this set / public int
size() return _sc.size() //
17
???? ???? ???????? 2

• / search and return the first Student that
  equals to s/
• public Student search(Student s)
• Student ans null
• for(int i0s!null ansnull
  iltthis.size()ii1)
• if(s.equals(at(i))) ans new Student(s)
• return ans
• / returns true iff s is already a member of
  this set. /
• public boolean member(Student s)
• return this.search(s)!null
• ??? ????? ?? add ???

18
???? ???? ???????? 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()

19
???? ???? ???????? 3
public class StudentContainer3 // data
members StudentContainer1 _sc
public Student search(Student s) return
at(find(s)) public Student search(long
id) return search(new Student(id,"Dammi")
)
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???? ???? ???????? 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! ")
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???? ???? ???????? 3
private void sort() for(int
i0iltsize()-1ii1) for(int
j0jltsize()-1jj1)
if(at(j1).smaller(at(j))) Student
tmp at(j1) _sc.update(at(j),j1) _sc.upda
te(tmp, j)
22
???? ???? ???? - Collection

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

23
???? ???? ???? - Collection

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

24
Object ??? (????????) ????????

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

25
???? ???? ???? - Collection

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

26
???? ???? ???? - 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 // ?????!!
28
????? ??????? ?? ???????

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

29
?????? ??? ???? ????????

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

30
???? ????????? ??????

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

31
???? ????????? ?????? - ?????

• 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

32
?? ????? ????

• ????? ? Object Oriented ??????
• ??????,
• ???? ???????? ????, ?????, ????.
• ???? ???? Object
• ????? ???? ????? (???)
• ???? ????????? ??????.