From 77b9796f4623f06470c568ee15fa00f2eb1a29d0 Mon Sep 17 00:00:00 2001
From: xuxin <840198532@qq.com>
Date: Tue, 3 Feb 2026 10:51:45 +0800
Subject: [PATCH] =?UTF-8?q?=E8=BF=9B=E9=98=B6day04-Map=E9=9B=86=E5=90=88?=
 =?UTF-8?q?=E5=AD=98=E5=82=A8=E8=87=AA=E5=AE=9A=E4=B9=89=E5=AF=B9=E8=B1=A1?=
 =?UTF-8?q?=EF=BC=88=E8=A6=81=E9=87=8D=E5=86=99hashCode&equals=EF=BC=89?=
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---
 .../src/com/inmind/map01/MapDemo04.java       | 33 ++++++++++++++++
 .../src/com/inmind/map01/Student.java         | 38 +++++++++++++++++++
 2 files changed, 71 insertions(+)
 create mode 100644 javaSE-day04/src/com/inmind/map01/MapDemo04.java
 create mode 100644 javaSE-day04/src/com/inmind/map01/Student.java

diff --git a/javaSE-day04/src/com/inmind/map01/MapDemo04.java b/javaSE-day04/src/com/inmind/map01/MapDemo04.java
new file mode 100644
index 0000000..05c1cf3
--- /dev/null
+++ b/javaSE-day04/src/com/inmind/map01/MapDemo04.java
@@ -0,0 +1,33 @@
+package com.inmind.map01;
+
+import java.util.HashMap;
+import java.util.HashSet;
+
+/*
+练习：每位学生（姓名，年龄）都有自己的家庭住址。那么，既然有对应关系，则将学生对象和家庭住址存储到map集合中。
+学生作为键, 家庭住址作为值。
+注意:学生姓名相同并且年龄相同视为同一名学生。
+
+
+总结:
+	1.hashMap存储自定义对象时,要实现去重,必须在自定义类中重写hashcode和equals
+	2.HashMap:底层是哈希表,它要实现去重,它跟hashcode和equals有关
+	3.HashSet底层就是HashMap.(查看源码),就是将Set中的数据作为map的键，而值永远是同一个常量
+ */
+public class MapDemo04 {
+    public static void main(String[] args) {
+        //定义出一个键为Student，值为String的双列集合
+        HashMap<Student, String> map = new HashMap<>();
+
+        map.put(new Student("张三", 18), "苏州");
+        map.put(new Student("李四", 19), "无锡");
+        map.put(new Student("王五", 20), "常州");
+        //业务上，我希望是王五从常州搬到了上海
+        map.put(new Student("王五", 20), "上海");
+
+        System.out.println(map);
+
+        HashSet<String> sets = new HashSet<>();
+        sets.add("1123");
+    }
+}
diff --git a/javaSE-day04/src/com/inmind/map01/Student.java b/javaSE-day04/src/com/inmind/map01/Student.java
new file mode 100644
index 0000000..88d31dd
--- /dev/null
+++ b/javaSE-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 +
+                '}';
+    }
+
+    //重写equals的目的：为了让2个内容相同的对象，看作是同一个
+    @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);
+    }
+
+    //重写hashCode的目的：为了让相同内容的对象，特征码（对象的哈希值）相同
+    @Override
+    public int hashCode() {
+        int result = Objects.hashCode(name);
+        result = 31 * result + age;
+        return result;
+    }
+}