From d77e9f903b42ee995f3eef5296b5b3a00f81cb41 Mon Sep 17 00:00:00 2001
From: xiongraorao <xiongraorao@gmail.com>
Date: Thu, 6 Sep 2018 10:00:51 +0800
Subject: [PATCH] update

---
 .../java/com/raorao/java/oop/Children.java    | 17 +++++
 .../main/java/com/raorao/java/oop/Client.java | 16 ++++
 .../main/java/com/raorao/java/oop/Father.java | 16 ++++
 interview/java/base.md                        | 75 +++++++++++++++++++
 interview/note.md                             |  4 +-
 5 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 code/src/main/java/com/raorao/java/oop/Children.java
 create mode 100644 code/src/main/java/com/raorao/java/oop/Client.java
 create mode 100644 code/src/main/java/com/raorao/java/oop/Father.java

diff --git a/code/src/main/java/com/raorao/java/oop/Children.java b/code/src/main/java/com/raorao/java/oop/Children.java
new file mode 100644
index 00000000..42033d65
--- /dev/null
+++ b/code/src/main/java/com/raorao/java/oop/Children.java
@@ -0,0 +1,17 @@
+package com.raorao.java.oop;
+
+/**
+ * 子类.
+ *
+ * @author Xiong Raorao
+ * @since 2018-09-06-9:27
+ */
+public class Children extends Father {
+
+  int sum = 2;
+  int chlid = 3;
+
+  public void say() {
+    System.out.println("this is children say!");
+  }
+}
diff --git a/code/src/main/java/com/raorao/java/oop/Client.java b/code/src/main/java/com/raorao/java/oop/Client.java
new file mode 100644
index 00000000..80460f8d
--- /dev/null
+++ b/code/src/main/java/com/raorao/java/oop/Client.java
@@ -0,0 +1,16 @@
+package com.raorao.java.oop;
+
+/**
+ * 测试.
+ *
+ * @author Xiong Raorao
+ * @since 2018-09-06-9:28
+ */
+public class Client {
+
+  public static void main(String[] args) {
+    Father f = new Children();
+    System.out.println(f.num);
+    f.say();
+  }
+}
diff --git a/code/src/main/java/com/raorao/java/oop/Father.java b/code/src/main/java/com/raorao/java/oop/Father.java
new file mode 100644
index 00000000..bb24b52b
--- /dev/null
+++ b/code/src/main/java/com/raorao/java/oop/Father.java
@@ -0,0 +1,16 @@
+package com.raorao.java.oop;
+
+/**
+ * 父类.
+ *
+ * @author Xiong Raorao
+ * @since 2018-09-06-9:26
+ */
+public class Father {
+  int num = 1;
+  public void say(){
+    System.out.println("this is father say!");
+  }
+}
+
+
diff --git a/interview/java/base.md b/interview/java/base.md
index ee9d16d8..d37cfde3 100644
--- a/interview/java/base.md
+++ b/interview/java/base.md
@@ -47,6 +47,11 @@
     - [静态内部类](#静态内部类)
 - [java 代码块](#java-代码块)
     - [代码块执行顺序](#代码块执行顺序)
+- [java 多态](#java-多态)
+    - [多态实现的几种方式](#多态实现的几种方式)
+    - [向上转型](#向上转型)
+    - [向下转型](#向下转型)
+    - [结论](#结论)
 - [参考文档](#参考文档)
 
 <!-- /TOC -->
@@ -964,6 +969,76 @@ Iterator it = s.iterator();得到的it的真正类型是KeyIterator，是Iterato
 
 静态代码块 > 构造代码块 > 构造函数
 
+# java 多态
+
+多态体现为父类引用变量可以指向子类对象：父类类型 变量名 = new 子类类型(); 
+
+1、多态的前提是必须有子父类关系或者类实现接口关系，否则无法完成多态。 
+2、在使用多态后的父类引用变量调用方法时，会调用子类重写后的方法。
+
+## 多态实现的几种方式
+
+1、普通父类多态
+
+``` java
+class A{
+}
+
+class B extends A{
+
+}
+
+A a = new B();
+```
+
+2、抽象类多态
+
+``` java
+abstract class A{
+
+}
+
+class B extends A{
+
+}
+
+A a = new B();
+```
+
+3、接口多态
+
+``` java
+interface A {
+
+}
+
+class B implements A{
+
+}
+
+A a = new B();
+
+```
+
+**同一个父类的方法会被不同的子类重写。在调用方法时，调用的为各个子类重写后的方法。**
+
+## 向上转型
+
+父类类型 变量名 = new 子类类型(); 
+
+## 向下转型
+
+子类类型 变量名 = (子类类型) 父类类型的变量; 
+
+如：Person p = new Student(); 
+Student stu = (Student) p 
+
+注意：如果是直接创建的父类对象，是无法向下转型为子类对象的。
+
+## 结论
+
+对于成员变量，看编译（静态）类型；
+对于成员方法，看运行（动态）类型；
 
 # 参考文档
 
diff --git a/interview/note.md b/interview/note.md
index 95cb9ab3..c3e00daf 100644
--- a/interview/note.md
+++ b/interview/note.md
@@ -51,7 +51,9 @@ Intel | 8.23 | 8.23(新投递) | 电面 | 8.24一面
 Keep | 8.31 | 8.31(新投递)
 小红书 | 8.31 | 8.31(新投递)
 中国银联 | 9.3 | 9.3（官网新投递）
-
+三七互娱 | 9.5 | 9.5(官网新投递)
+去哪儿网 | 9.5 | 9.5(官网新投递)
+搜狗 | 9.5 | 9.5(官网新投递)
 
 # 2 复习内容