diff --git a/s-day03/src/com/inmind/set02/LinkedHashSetDemo09.java b/s-day03/src/com/inmind/set02/LinkedHashSetDemo09.java
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+++ b/s-day03/src/com/inmind/set02/LinkedHashSetDemo09.java
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+package com.inmind.set02;
+
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.LinkedList;
+
+/*
+LinkedHashSet的特点
+1.存取有序
+2.没有索引
+3.不能重复
+
+LinkedHashSet的底层数据结构：在哈希表的基础上，添加了链表,它是HashSet的子类
+哈希表：去重，高效查询
+链接：保证数据的顺序
+
+注意：当我们定义的集合既要去重，也要保证顺序，采用LinkedHashSet
+ */
+public class LinkedHashSetDemo09 {
+    public static void main(String[] args) {
+        Student s1 = new Student("刘备1", 20);
+        Student s2 = new Student("刘备2", 19);
+        Student s3 = new Student("刘备3", 21);
+        Student s4 = new Student("刘备3", 21);
+        Student s5 = new Student("刘备3", 21);
+        LinkedHashSet<Student> sets = new LinkedHashSet<>();
+        sets.add(s1);
+        sets.add(s2);
+        sets.add(s3);
+        sets.add(s4);
+        sets.add(s5);
+        System.out.println(sets);
+    }
+}