강제 타입 변환 코드

package com.day3;

public class Parent {
	public String field1;
	
	public void method1() {
		System.out.println("Parent-method1()");
	}
	
	public void method2() {
		System.out.println("Parent-method2()");
	}
}

부모 클래스

 

package com.day3;

public class Child extends Parent{
	public String field2;
	
	public void method3() {
		System.out.println("Child-method3()");
	}
}

자식 클래스 

package com.day3;

public class ChildExample {

	public static void main(String[] args) {
		Parent parent = new Child();  //자동 타입변환
		parent.field1 = "data1";
		parent.method1();
		parent.method2();
		/*
		parent.field2 = "date2";
		parent.method3();         얘네 둘은 불가넝 
		 */
		
		Child child = (Child) parent; //강제 타입변환 
		child.field2 = "yyy";    //가능
		child.method3();    //가능
	}
}

강제 타입 변환