[JAVA] Object 클래스

Object 클래스

- 모든 클래스 상속계층도의 최상위 조상클래스
- 자바의 기본 패키지 (java.lang)에 선언되어 있음
- 자바의 모든 클래스는 무조건 Object클래스를 상속 받는다
- 자바의 모든 클래스는 Object클래스의 후손들이다 -> true

package oop0320;

import java.lang.*; //생략가능하다

class Jeju extends Object {
	@Override
	public String toString() {
		return "제주도";
	}
}//class end

class Suwon extends Object {
	private String id="itwill";
	private String pw="1234";
	
	@Override
	public String toString() {
		return "Suwon [id=" + id + ", pw=" + pw + "]";
	}
}//class end

class Incheon extends Object {
	private String name="인천 광역시";
	private String phone="789-8745";
	
	@Override
	public String toString() {
		return "Incheon [name=" + name + ", phone=" + phone + "]";
	}
	
	
}//class end

class Seoul {}//class end


public class Test02_Object extends Object{ //extends Object 생략가능

	public static void main(String[] args) {

			Jeju je=new Jeju();
			System.out.println(je.toString());
			
			Suwon su=new Suwon();
			System.out.println(su.toString());
			
			Incheon in=new Incheon();
			System.out.println(in.toString());
			
			//함수 이름 toSting() 생략 가능
			System.out.println(je);
			System.out.println(su);
			System.out.println(in);
			
			
			Seoul se=new Seoul();
			System.out.println(se);

			se=null;
			System.out.println(se);

	}//main() end
}//class end