instanceof 연산자

package day08;
class Box{
 
}

class PaperBox extends Box{
 
}

class GoldPaperBox extends PaperBox{
 
}

public class InstanceOfTest {
 public static void wrapBox(Box box){
  System.out.println("GoldPaperBox:"+(box instanceof GoldPaperBox));
  System.out.println("PaperBox:"+(box instanceof PaperBox));
  System.out.println("Box:"+(box instanceof Box));
  System.out.println();
 }
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  Box box1 = new Box();
  PaperBox box2 = new PaperBox();
  GoldPaperBox box3 = new GoldPaperBox();
  
  wrapBox(box3);
  wrapBox(box2);
  wrapBox(box1);
 }
}
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결과
GoldPaperBox:true
PaperBox:true
Box:true

GoldPaperBox:false
PaperBox:true
Box:true

GoldPaperBox:false
PaperBox:false
Box:true
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instanceof 연산자는 상위 클래스와 자기 자신 클래스까지 허용한다.