double obj=1;
 if(obj instanceof Double){
 System.out.println("true");
 }

　 String obj=1.0+"";
 if(obj instanceof Double){
 System.out.println("true");
 }

　if(null instanceof Object){
 System.out.println("true");
 }else{
 System.out.println("false");
 }
 String obj=null;
 if(obj instanceof Object){
 System.out.println("true");
 }else{
 System.out.println("false");
 }

　if(obj instanceof null){
 System.out.println("true");
 }else{
 System.out.println("false");
 }

public class Test {
 public static void main(String[] args){
 System.out.println(new Student() instanceof String); //compile time error
 System.out.println(new Student() instanceof Exception); //compile time error
 System.out.println(new Student() instanceof Object); //compilation and output true
 System.out.println(new Student() instanceof List); //compilation and output false
 System.out.println(new Student() instanceof List<?>); //compilation and output false
 System.out.println(new Student() instanceof List<String>); //compile time error
 System.out.println(new Student() instanceof List<Object>); //compile time error
 System.out.println(new String() instanceof List); //compile time error
 System.out.println(new String() instanceof List<?>); //compile time error
 System.out.println(null instanceof Object); //compilation and output false 
 
 }
}
class Student{ 
}

package com.instanceoftest;
 interface A{}
 class B implements A{
 }
 class C extends B {
 }
 class instanceoftest {
 public static void main(String[] args){
 A a=null;
 B b=null;
 boolean res; 
 System.out.println("instanceoftest test case 1: ------------------");
 res = a instanceof A; 
 System.out.println("a instanceof A: " + res);
 res = b instanceof B;
 System.out.println("b instanceof B: " + res);
 System.out.println("/ninstanceoftest test case 2: ------------------"); 
 a=new B();
 b=new B();
 res = a instanceof A; 
 System.out.println("a instanceof A: " + res);
 res = a instanceof B;
 System.out.println("a instanceof B: " + res);
 res = b instanceof A;
 System.out.println("b instanceof A: " + res);
 res = b instanceof B;
 System.out.println("b instanceof B: " + res);
 System.out.println("/ninstanceoftest test case 3: ------------------");
 B b2=(C)new C();
 res = b2 instanceof A;
 System.out.println("b2 instanceof A: " + res);
 res = b2 instanceof B;
 System.out.println("b2 instanceof B: " + res);
 res = b2 instanceof C;
 System.out.println("b2 instanceof C: " + res);
 }
}
/*
result:
instanceoftest test case 1: ------------------
a instanceof A: false
b instanceof B: false
instanceoftest test case 2: ------------------
a instanceof A: true
a instanceof B: true
b instanceof A: true
b instanceof B: true
instanceoftest test case 3: ------------------
b2 instanceof A: true
b2 instanceof B: true
b2 instanceof C: true
*/