From df9c7fc6f967d6755c7e7a3c43bf8f624ff0cca6 Mon Sep 17 00:00:00 2001
From: xuxin <840198532@qq.com>
Date: Sun, 25 Jan 2026 11:04:49 +0800
Subject: [PATCH] =?UTF-8?q?day09-=E7=94=A8instanceof=E5=85=B3=E9=94=AE?=
 =?UTF-8?q?=E5=AD=97=E8=BF=9B=E8=A1=8C=E7=B1=BB=E5=9E=8B=E5=88=A4=E6=96=AD?=
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---
 .../com/inmind/duotai08/downcast/Demo11.java  | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 day10/src/com/inmind/duotai08/downcast/Demo11.java

diff --git a/day10/src/com/inmind/duotai08/downcast/Demo11.java b/day10/src/com/inmind/duotai08/downcast/Demo11.java
new file mode 100644
index 0000000..81ace72
--- /dev/null
+++ b/day10/src/com/inmind/duotai08/downcast/Demo11.java
@@ -0,0 +1,38 @@
+package com.inmind.duotai08.downcast;
+/*
+如何在代码中判断出当前的多态父类类型是不是对应的子类类型呢？
+instanceof 关键字
+    多态类型 instanceof 子类类型 会有一个返回值 boolean
+    true: 多态类型就是子类类型，（animal是一个猫）
+    false:多态类型就不是子类类型，（animal不是一个猫）
+ */
+public class Demo11 {
+    public static void main(String[] args) {
+        //来一只狗
+        Dog dog = new Dog();
+        //来一只猫
+        Cat cat = new Cat();
+        //假设每个子类对象都要执行同一段代码，再调用eat，并调用各自的独有的功能
+        work(dog);
+        work(cat);
+    }
+
+    //使用多态的好处，定义一个方法
+    public static void work(Animal animal) {//多态的好用，向上转型
+        System.out.println(1);
+        System.out.println(2);
+        System.out.println(3);
+        animal.eat();
+
+        //在进行向下转型时，必须先判断是否是该类型
+        if (animal instanceof Dog) {
+            Dog d = (Dog) animal;
+            d.watchDoor();
+        }
+
+        if (animal instanceof Cat) {
+            Cat c = (Cat) animal;
+            c.catchMouse();
+        }
+    }
+}