면접 질문 # 다형성

1. 오버로딩과 다형성

서로 다른 동작 방법을 가지고 있기 때문에 오버로딩은 다형성의 한 예라고 할 수 있다.

package 다형성;


class a{
	public void a(int param) {
		System.out.println("숫자출력");
		System.out.println(param);
	}
	public void a(String param) {
		System.out.println("문자 출력");
		System.out.println(param);
	}
		
}

public class overloading_polymorphism {
	public static void main(String[] args) {
		a a = new a();
		a.a(3);
		a.a("삼");
	}
}

 

2. 클래스와 다형성

package polymorphism;

class ClassA{
	public String x() {return "ClassA.x";}
}
class ClassB extends ClassA{
	public String x() {return "ClassB.x";}
	public String y() {return "ClassB.y";}
}
public class class_ploymorphism {
public static void main(String[] args) {
	ClassA obj = new ClassB();
	System.out.println(obj.x());
//	System.out.println(obj.y());
}
}

package org.opentutorials.javatutorials.polymorphism;
abstract class Calculator{
    int left, right;
    public void setOprands(int left, int right){
        this.left = left;
        this.right = right;
    } 
    int _sum() {
        return this.left + this.right;
    }
    public abstract void sum();  
    public abstract void avg();
    public void run(){
        sum();
        avg();
    }
}
class CalculatorDecoPlus extends Calculator {
    public void sum(){
        System.out.println("+ sum :"+_sum());
    }
    public void avg(){
        System.out.println("+ avg :"+(this.left+this.right)/2);
    }
} 
class CalculatorDecoMinus extends Calculator {
    public void sum(){
        System.out.println("- sum :"+_sum());
    }
    public void avg(){
        System.out.println("- avg :"+(this.left+this.right)/2);
    }
} 
public class CalculatorDemo {
    public static void execute(Calculator cal){
        System.out.println("실행결과");
        cal.run();
    }
    public static void main(String[] args) { 
        Calculator c1 = new CalculatorDecoPlus();
        c1.setOprands(10, 20);
         
        Calculator c2 = new CalculatorDecoMinus();
        c2.setOprands(10, 20);
         
        execute(c1);
        execute(c2);
    }
}

 

3. 인터페이스와 다형성

package org.opentutorials.javatutorials.polymorphism;
 
interface father{}
interface mother{}
interface programmer{
    public void coding();
}
interface believer{}
class Steve implements father, programmer, believer{
    public void coding(){
        System.out.println("fast");
    }
}
class Rachel implements mother, programmer{
    public void coding(){
        System.out.println("elegance");
    }
}
public class Workspace{
    public static void main(String[] args){
        programmer employee1 = new Steve();
        programmer employee2 = new Rachel();
         
        employee1.coding();
        employee2.coding();
    }
}

 

참조: 생활코딩 다형성