Java关键字instanceof

interface IObject {
}

class Foo implements IObject{
}

class Test extends Foo{
}

public class MultiStateTest {
public static void main(String args[]){
test();
}

public static void test(){
IObject f=new Test();
if(f instanceof java.lang.Object)System.out.println("true");
if(f instanceof Foo)System.out.println("true");
if(f instanceof Test)System.out.println("true");
if(f instanceof IObject)System.out.println("true");
}
}

true
true
true
true