Transcript JSP คืออะไร

การโปรแกรมเชิงวัตถุดวยภาษา
JAVA
้
Object-Oriented Programming
มหาวิทยาลัยเนชัน
่
http://www.nation.ac.th
http://www.thaiall.com/class
บุรน
ิ ทร ์
รุจจนพันธุ ์
.
โปรแกรมภาษาจาวา
class human {
public static void main (String args[])
System.out.println(“wow”);
}
}
http://www.thaiall.com/class
{
หลักพืน
้ ฐานของ OO in
Java
1. Inheritance
2. Encapsulation
3. Polymorphism
3.1 Overloading
3.2 Overriding
http://www.thaiall.com/class
Inheritance
class father {
void homeaddr(){System.out.println(“lp”);}
}
class child extends father {
public static void main (String args[]) {
homeaddr();
}
}
http://www.thaiall.com/class
Encapsulation
class friend {
private int val;
public int getter(){ return this.val;}
public void setter(int a){ this.val=a;}
}
class child {
public static void main (String args[]) {
friend x = new friend();
x.setter(5);
System.out.println(x.getter());
}
}
http://www.thaiall.com/class
Polymorphism :
Overloading
overloaded methods:
- appear in the same class or a subclass
- have the same name but,
- have different parameter lists, and,
- can have different return type
http://www.thaiall.com/class
Polymorphism :
Overloading
class child {
static int bag(){ return 1; }
static int bag(int a){ return a; }
static int bag(String a){ return a.length(); }
public static void main (String args[]) {
System.out.println(bag());
System.out.println(bag(5));
System.out.println(bag(“abc”));
}
}
http://www.thaiall.com/class
Polymorphism :
Overriding
overriding methods:
- appear in subclasses have the same name as a superclass method
- have the same parameter list as a superclass method
- have the same return type as as a superclass method
- the access modifier for the overriding method may not be more
restrictive than the access modifier of the superclass method
if the superclass method is public, the overriding method must be public
if the superclass method is protected, the overriding method may be
protected or public
if the superclass method is package, the overriding method may be
packagage, protected, or public
if the superclass methods is private, it is not inherited and overriding
is not an issue
- the throws clause of the overriding method may only include
exceptions that can be thrown by the superclass method, including
it's subclasses
http://www.thaiall.com/class
Polymorphism :
Overriding (1/2)
class father {
static void addr(){System.out.println(“lp”);}
}
class child extends father {
static void addr(){System.out.println(“cm”);}
public static void main (String args[]) {
addr();
new father().addr();
}
}
http://www.thaiall.com/class
Polymorphism :
class father {
Overriding
(2/2)
void addr(){System.out.println(“lp”);}
}
class child extends father {
void addr(){System.out.println(“cm”);}
public static void main (String args[]) {
child c = new child();
c.addr();
}
}
http://www.thaiall.com/class