From ed3c312e1f05ca67b3cfd8ba8d0617f49f3cfe88 Mon Sep 17 00:00:00 2001
From: xuxin <840198532@qq.com>
Date: Thu, 15 Oct 2026 13:46:20 +0800
Subject: [PATCH] =?UTF-8?q?s-day04--Map=E9=9B=86=E5=90=88=E5=AD=98?=
 =?UTF-8?q?=E5=82=A8=E8=87=AA=E5=AE=9A=E4=B9=89=E5=AF=B9=E8=B1=A1?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 s-day04/src/com/inmind/map01/MapDemo04.java | 33 ++++++++++++++++++
 s-day04/src/com/inmind/map01/Student.java   | 38 +++++++++++++++++++++
 2 files changed, 71 insertions(+)
 create mode 100644 s-day04/src/com/inmind/map01/MapDemo04.java
 create mode 100644 s-day04/src/com/inmind/map01/Student.java

diff --git a/s-day04/src/com/inmind/map01/MapDemo04.java b/s-day04/src/com/inmind/map01/MapDemo04.java
new file mode 100644
index 0000000..c4b5c21
--- /dev/null
+++ b/s-day04/src/com/inmind/map01/MapDemo04.java
@@ -0,0 +1,33 @@
+package com.inmind.map01;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+
+/*
+5.Map集合存储自定义对象
+需求：每位学生(姓名，年龄)都有自己的家庭住址，我要把学生对象和居住城市存储到Map集合中，学生作为键key，居住城市作为值
+注意：学生姓名和年龄如果相同看作同一个学生
+
+哈希：通过hashCode，equals实现去重
+
+总结：
+1.hashMap存储自定义对象作为key时，要实现去重，必须在自定义类中重写hashCode，equals方法
+2.HashMap：底层数据结构就是哈希表，它跟对象哈希值有关
+3.HashSet 底层就是HashMap,HashMap<E,Object>,将set中的值作为map中的key，而map中值没有任何作用，就保存相同的数据
+ */
+public class MapDemo04 {
+    public static void main(String[] args) {
+        Map<Student, String> map = new HashMap<>();
+        map.put(new Student("张三1", 19), "上海");
+        map.put(new Student("张三2", 18), "苏州");
+        map.put(new Student("张三3", 21), "常州");
+        map.put(new Student("张三1", 19), "上海");
+
+        System.out.println(map);
+
+        HashSet<String> hashSet = new HashSet<>();
+        hashSet.add("");
+
+    }
+}
diff --git a/s-day04/src/com/inmind/map01/Student.java b/s-day04/src/com/inmind/map01/Student.java
new file mode 100644
index 0000000..27fb5d0
--- /dev/null
+++ b/s-day04/src/com/inmind/map01/Student.java
@@ -0,0 +1,38 @@
+package com.inmind.map01;
+
+import java.util.Objects;
+
+public class Student {
+    String name;
+    int age;
+
+    public Student(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "Student{" +
+                "name='" + name + '\'' +
+                ", age=" + age +
+                '}';
+    }
+
+    //要实现去重，必定要重写hashCode，equals方法
+
+    @Override
+    public boolean equals(Object o) {
+        if (o == null || getClass() != o.getClass()) return false;
+
+        Student student = (Student) o;
+        return age == student.age && Objects.equals(name, student.name);
+    }
+
+    @Override
+    public int hashCode() {
+        int result = Objects.hashCode(name);
+        result = 31 * result + age;
+        return result;
+    }
+}