diff --git a/day07/src/com/inmind/arraylist03/Demo09.java b/day07/src/com/inmind/arraylist03/Demo09.java
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+++ b/day07/src/com/inmind/arraylist03/Demo09.java
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+package com.inmind.arraylist03;
+
+import java.util.ArrayList;
+
+/*
+常用类-ArrayList-练习2_添加对象
+ */
+public class Demo09 {
+    //创建一个保存book对象的容器，添加3本书，通过集合遍历判断出哪本书最贵
+    public static void main(String[] args) {
+        ArrayList<Book> bookList = new ArrayList<>();
+        //先创建3本书，或者在添加时，进行创建
+        //Book book1 = new Book("b001", "书1", 10.0, "2020-1-1");
+        Book book2 = new Book("b001", "书2", 10.0, "2020-1-1");
+        Book book3 = new Book("b001", "书3", 50.0, "2020-1-1");
+        bookList.add(new Book("b001", "书1", 30.0, "2020-1-1"));
+        bookList.add(book2);
+        bookList.add(book3);
+        //集合的变量
+        Book maxBook = bookList.get(0);
+        for (int i = 0; i < bookList.size(); i++) {
+            Book book = bookList.get(i);
+            if (book.getPrice() > maxBook.getPrice()) {
+                maxBook = book;
+            }
+        }
+        maxBook.showBook();
+    }
+}