初始化

.gitignore

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+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store

.idea/.gitignore

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+# 默认忽略的文件
+/shelf/
+/workspace.xml
+# 基于编辑器的 HTTP 客户端请求
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/encodings.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding" defaultCharsetForPropertiesFiles="UTF-8">
+    <file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
+    <file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
+    <file url="PROJECT" charset="UTF-8" />
+  </component>
+</project>

.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+    <option name="workspaceImportForciblyTurnedOn" value="true" />
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.example</groupId>
+    <artifactId>rikao7</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <dependencies>
+        <!-- lombok依赖 -->
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.22</version>
+        </dependency>
+    </dependencies>
+
+</project>

src/main/java/org/example/StudentApplication.java

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+package org.example;
+
+import org.example.domain.Student;
+
+import java.math.BigDecimal;
+import java.util.HashMap;
+import java.util.Map;
+
+public class StudentApplication {
+    public static void main(String[] args) {
+
+
+        // 设置编码（仅在需要时启用）
+        try {
+            System.setOut(new java.io.PrintStream(System.out,true,"UTF-8"));
+        } catch (java.io.UnsupportedEncodingException e) {
+            System.err.println("无法设置UTF-8编码：" + e.getMessage());
+        }
+
+        //创建HashMap对象
+        HashMap<Integer, Student> studentHashMap = new HashMap<>();
+
+        //创建两个学生对象
+        Student studentOne = new Student(1, "梦钰", 22, "男", new BigDecimal(100));
+        Student studentTwo = new Student(2, "钰萍", 18, "女", new BigDecimal(100));
+
+        //保存到HashMap集合中，键为学生编号，值为学生对象
+        studentHashMap.put(studentOne.getStudentId(),studentOne);
+        studentHashMap.put(studentTwo.getStudentId(),studentTwo);
+
+
+        System.out.println("第一种entrySet遍历方法:");
+        for (Map.Entry<Integer, Student> studentEntry : studentHashMap.entrySet()) {
+            System.out.println("key：" + studentEntry.getKey() + " value：" + studentEntry.getValue());
+        }
+
+        System.out.println("\n第二种keySet遍历方法:");
+        for (Integer student : studentHashMap.keySet()) {
+            System.out.println("key：" + student + " value：" + studentHashMap.get(student));
+        }
+
+
+        System.out.println("\n第三种values遍历方法:");
+        for (Student student : studentHashMap.values()) {
+            System.out.println( " value：" + student);
+        }
+    }
+}

src/main/java/org/example/domain/Student.java

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+package org.example.domain;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import java.math.BigDecimal;
+
+/**
+ * 学生实体类
+ * 定义一个学生类Student，包括学生姓名，年龄，性别，成绩基本信息
+ */
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+public class Student {
+    /**
+     * 学生编号
+     */
+    private Integer studentId;
+    /**
+     * 学生名称
+     */
+    private String studentName;
+    /**
+     * 学生年龄
+     */
+    private Integer studentAge;
+    /**
+     * 学生性别
+     */
+    private String studentSex;
+    /**
+     * 学生成绩
+     */
+    private BigDecimal studentScore;
+}