From 2ae95bc5fe5aae847bed0f6d8cbc280c072abd49 Mon Sep 17 00:00:00 2001
From: xuxin <840198532@qq.com>
Date: Sat, 31 Jan 2026 15:01:08 +0800
Subject: [PATCH] =?UTF-8?q?=E8=BF=9B=E9=98=B6day02-=E6=B3=9B=E5=9E=8B?=
 =?UTF-8?q?=E9=80=9A=E9=85=8D=E7=AC=A6=E7=9A=84=E4=B8=8A=E4=B8=8B=E9=99=90?=
 =?UTF-8?q?(=E5=8F=97=E9=99=90=E6=B3=9B=E5=9E=8B)(=E4=BA=86=E8=A7=A3)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../src/com/inmind/generic_advance06/Demo07.java | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/javaSE-day02/src/com/inmind/generic_advance06/Demo07.java b/javaSE-day02/src/com/inmind/generic_advance06/Demo07.java
index 08cd103..69705a6 100644
--- a/javaSE-day02/src/com/inmind/generic_advance06/Demo07.java
+++ b/javaSE-day02/src/com/inmind/generic_advance06/Demo07.java
@@ -5,6 +5,12 @@ import java.util.ArrayList;
  13.泛型通配符的使用(了解)
     当我们想接收一个数据类型，它们的泛型不一致，但是方法中的操作是一致的时候，如果操作？？？？
     泛型通配符:?,它的作用是能够匹配任意的泛型类型
+
+    ---------------------------------------------------
+    格式:
+    <? extends B> :泛型的类型只能是B类型或者B类型的子类；上限
+    <? super B> :  泛型的类型只能是B类型或者B类型的父类；下限
+
  */
 public class Demo07 {
     public static void main(String[] args) {
@@ -35,11 +41,17 @@ public class Demo07 {
             System.out.println(s);
         }*/
         show(sLists);
+
+//        show(new ArrayList<Object>());
     }
     //注意：ArrayList<Object>参数类型时，泛型是没有多态！！！！
-    public static void show(ArrayList<?> list){
-        for (Object o : list) {
+    public static void show(ArrayList<? extends Person> list){//上限，只能是Person及其子类
+//    public static void show(ArrayList<? super Person> list){//下限，只能是Person及其父类
+        /*for (Object o : list) {
             System.out.println(o);
+        }*/
+        for (Person p : list) {
+            System.out.println(p);
         }
     }