[12일차 오후]

오버로딩
- 리턴타입을 맞출 필요는 없다	부모 public void setA(){....} 자식 public int setA(int a){.........}
- 상속관계에서도 오버로딩이 존재한다.	부모 1) public void md(){....} //하이딩         2) public void md(int a){....} 자식클래스 extends 부모클래스          3) public void md( ){....} //오버라이드         4) public void md(String a){....}
오버라이딩
- 반드시 재정의(덮어쓰기) + 리턴타입까지 동일해야	부모 void setA(int a){....} 자식 [default / protected / public] void setA(int a){.........}

CastingTest03.java

package inheritance;

class Person1 {
	private String name;
	
	public Person1(String name) {
		this.name = name;
	}
	
	public void setName(String name) {
		this.name = name;
	}

	public String getName() {
		return name;
	}
}

class Student1 extends Person1 {
	private String dept; //null
	
	public Student1(String name) {
		super(name);
	}
	
	public void setDept(String dept) {
		this.dept = dept;
	}
	
	public String getDept() {
		return dept;
	}
}

public class CastingTest03 {
	public static void main(String[] args) {
		//업캐스팅 선행
		Person1 person1 = new Student1("Dully"); //Pa Cha
		
		//다운캐스팅, 명시적형변환, 강제변환
		Student1 student1 = (Student1) person1; //여기에서만 다운캐스팅일어남 C-C
//		Student1 student1 = (Student1) new person1("MadPlay"); //person1자료값만 있어서 오류남
		
//		student1.setName("Cogildong");
//		person1.setName("Cogildong"); //person1 가능
		String strName = student1.getName();
//		String strName = person1.getName(); //person1 가능
		
//		student1.setDept("Computer Eng"); // p-c에서 
		String strDept = student1.getDept(); //같은 주소값에서 cc값만
		System.out.println(strName + ", " + strDept);
		
		
	}
}​

Dully, null

CastingTest04.java

package inheritance;

class PUnit { int u = 1;}
class Unit1 extends PUnit { int u1 = 2; }
class Unit2 extends Unit1 { int u2 = 3; }
class Unit3 extends Unit2 { int u3 = 5; }


public class CastingTest04 {
	public static void main(String[] args) {
		Unit2 unit1 = new Unit2(); // P, U1, U2
		Unit3 unit2 = new Unit3(); // P, U1, U2, U3
		
		int result = unit1.u + unit1.u1 + unit1.u2; // 1+2+3=6
		int result1 = unit2.u + unit2.u1 + unit2.u2 + unit2.u3; //1+2+3+5=11
		System.out.println(
				"1번: " + + unit1.u + " + " + unit1.u1 + " + " + unit1.u2 + " = " + result);
		System.out.println(
				"2번: " + + unit2.u + " + " + unit2.u1 + " + " + unit2.u2 +  " + " + unit2.u3 + " = " + result);
		System.out.println("==============================");
		
		System.out.println("0번: " + (unit1 instanceof PUnit));
		System.out.println("1번: " + (unit1 instanceof Unit1));
		System.out.println("2번: " + (unit1 instanceof Unit2));

		System.out.println("3번: " + (unit2 instanceof PUnit));
		System.out.println("4번: " + (unit2 instanceof Unit1));
		System.out.println("5번: " + (unit2 instanceof Unit2));
		System.out.println("6번: " + (unit2 instanceof Unit3));

	}

}​

1번: 1 + 2 + 3 = 6
2번: 1 + 2 + 3 + 5 = 6
==============================
0번: true
1번: true
2번: true
3번: true
4번: true
5번: true
6번: true

package inheritance;

public class Customer {
	
	protected int customerID;
	protected String customerName;
	protected String customerGrade;
	int bonusPoint;
	double bonusRatio;
	
	public Customer()
	{
		customerGrade = "SILVER";
		bonusRatio = 0.01;
		System.out.println("Cusomer() 생성자 호출");
	}
	
	public Customer(int customerID, String customerName){
		this.customerID = customerID;
		this.customerName = customerName;
		customerGrade = "SILVER";
		bonusRatio = 0.01;
		System.out.println("Cusomer(int, String) 생성자 호출");
	}
	
	public int calcPrice(int price){
		bonusPoint += price * bonusRatio;
		return price;
	}
	
	public String showCustomerInfo(){
		return customerName + " 님의 등급은 " + customerGrade + "이며, 보너스 포인트는 " + bonusPoint + "입니다.";  
	}
	
	public int getCustomerID() {
		return customerID;
	}

	public void setCustomerID(int customerID) {
		this.customerID = customerID;
	}

	public String getCustomerName() {
		return customerName;
	}

	public void setCustomerName(String customerName) {
		this.customerName = customerName;
	}

	public String getCustomerGrade() {
		return customerGrade;
	}

	public void setCustomerGrade(String customerGrade) {
		this.customerGrade = customerGrade;
	}

}

package inheritance;

public class CustomerTest1 {

	public static void main(String[] args) {
//		Customer customerLee = new Customer(10010, "이순신");
		Customer customerLee = new Customer();
		customerLee.setCustomerID(10010);
		customerLee.setCustomerName("이순신");
		customerLee.bonusPoint = 1000;
		System.out.println(customerLee.showCustomerInfo());

//		VIPCustomer customerKim = new VIPCustomer(10020, "김유신", 12345);
		VIPCustomer customerKim = new VIPCustomer();
		customerKim.setCustomerID(10020);
		customerKim.setCustomerName("김유신");
		customerKim.bonusPoint = 10000;
		System.out.println(customerKim.showCustomerInfo());
	}
}

package inheritance;

public class VIPCustomer extends Customer{

	private int agentID;
	double saleRatio;
	
	public VIPCustomer()
	{   //super() 숨겨져있음
		customerGrade = "VIP";
		bonusRatio = 0.05;
		saleRatio = 0.1;
	}
	
	public VIPCustomer(int customerID, String customerName, int agentID){
		super(customerID, customerName); //super기타생성자 숨길 수 없다.
		customerGrade = "VIP";
		bonusRatio = 0.05;
		saleRatio = 0.1;
		this.agentID = agentID;
	}
	
	public int calcPrice(int price){
		bonusPoint += price * bonusRatio;
		return price - (int)(price * saleRatio);
	}
	
	public int getAgentID(){
		return agentID;
	}
	
	
}

Cusomer() 생성자 호출
이순신 님의 등급은 SILVER이며, 보너스 포인트는 1000입니다.
Cusomer() 생성자 호출
김유신 님의 등급은 VIP이며, 보너스 포인트는 10000입니다.