From d7f3149cb2659b1f8e1846a935b97a43ac0b87fe Mon Sep 17 00:00:00 2001
From: xuxin <840198532@qq.com>
Date: Mon, 29 Dec 2025 15:26:11 +0800
Subject: [PATCH] =?UTF-8?q?day07-=E5=9F=BA=E6=9C=AC=E6=95=B0=E6=8D=AE?=
 =?UTF-8?q?=E7=B1=BB=E5=9E=8B=E7=9A=84=E8=87=AA=E5=8A=A8=E6=8B=86=E8=A3=85?=
 =?UTF-8?q?=E7=AE=B1?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 day07/src/com/inmind/arraylist03/Demo11.java | 48 ++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 day07/src/com/inmind/arraylist03/Demo11.java

diff --git a/day07/src/com/inmind/arraylist03/Demo11.java b/day07/src/com/inmind/arraylist03/Demo11.java
new file mode 100644
index 0000000..e6c92d4
--- /dev/null
+++ b/day07/src/com/inmind/arraylist03/Demo11.java
@@ -0,0 +1,48 @@
+package com.inmind.arraylist03;
+
+import java.util.ArrayList;
+
+/*
+基本类型	基本类型包装类
+byte	Byte
+short	Short
+int	    Integer
+long	Long
+float	Float
+double	Double
+char	Character
+boolean	Boolean
+
+主要记录int和char的包装类
+
+自动装箱：int型的值------装箱成Integer类的对象
+自动拆箱：Integer类的对象----拆箱为int型的值
+ */
+public class Demo11 {
+    public static void main(String[] args) {
+        //定义一个保存int值的集合
+        ArrayList<Integer> integers = new ArrayList<>();
+        integers.add(1);//自动装箱：1---装箱为内容为1的Integer对象
+        integers.add(2);
+        integers.add(3);
+        System.out.println(integers);
+
+        //获取下integers中的第二个的内容(对象)
+        Integer i = integers.get(1);
+        int result = i+10;//自动拆箱：i是Integer类的对象----拆箱为int型的值2
+        System.out.println(result);//12
+
+
+        //保存double小数的集合
+        ArrayList<Double> doubles = new ArrayList<>();
+
+        doubles.add(1.0);//自动装箱：double1.0  ---装箱为内容为1.0的Double对象
+        doubles.add(2.0);
+        doubles.add(3.0);
+        System.out.println(doubles);
+        double d = 4;//自动类型提升：int--->double 4.0
+        Double d1 = d;//自动装箱
+        doubles.add(d1);
+        System.out.println(doubles);
+    }
+}