s-day01-Object概述

s-day01/src/com/inmind/object01/Demo01.java

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+package com.inmind.object01;
+/*
+Object类:所有类的父类【祖宗类】，java中所有的类直接或者间接继承自Object
+ */
+public class Demo01 {
+    public static void main(String[] args) {
+        Person p = new Person();
+        Student s = new Student();
+        //Object类的多态
+        Object o1 = p;
+        Object o2 = new Person();
+        Object o3 = new Student();
+        //Object是可以接受任意引用数据类型！！！！！
+        Object o4 = "123";
+        method(p);
+        method(s);
+        method("abc");
+    }
+
+    public static Object method(Object o) {
+        return null;
+    }
+}

s-day01/src/com/inmind/object01/Person.java

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+package com.inmind.object01;
+//直接继承Object类
+public class Person extends Object{
+}

s-day01/src/com/inmind/object01/Student.java

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+package com.inmind.object01;
+//间接继承Object类
+public class Student extends Person{
+}