diff --git "a/work/com/java/minxi/java_20240426/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java" "b/work/com/java/minxi/java_20240426/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java"
index 87fa4c362927ffc85dd4b4ecfa0f10bf8394024c..a60d01e5807faf7382e190c621db258e98fd673e 100644
--- "a/work/com/java/minxi/java_20240426/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java"
+++ "b/work/com/java/minxi/java_20240426/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java"
@@ -4,6 +4,11 @@ public class Animal {
     //包含属性name和age
     public String name;
     public int age;
+
+    public Animal() {
+
+    }
+
     //并定义一个方法showInfo用于展示动物的信息
     public void showInfo() {
         System.out.println("Name: " + name + " Age: " + age);
diff --git "a/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java" "b/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java"
new file mode 100644
index 0000000000000000000000000000000000000000..4ce8984e92772db38d6c4093191177411b56edd0
--- /dev/null
+++ "b/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Animal.java"
@@ -0,0 +1,4 @@
+package com.java.minxi.java_20240515.java_2302_郑祺海_2344310215;
+
+public class Animal {
+}
diff --git "a/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/mapMain.java" "b/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/mapMain.java"
index f8e14e68a44e27e89a1f25f61fcc956be99aaedc..60b848a92ecb323ca9a5498df1f8d23b3ac1af21 100644
--- "a/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/mapMain.java"
+++ "b/work/com/java/minxi/java_20240515/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/mapMain.java"
@@ -1,5 +1,7 @@
 package com.java.minxi.java_20240515.java_2302_郑祺海_2344310215;
 
+import com.java.minxi.java_20240426.java_2302_郑祺海_2344310215.Animal;
+
 import java.util.*;
 
 public class mapMain {
diff --git "a/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/BigDecimalExample.java" "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/BigDecimalExample.java"
new file mode 100644
index 0000000000000000000000000000000000000000..fe90d5cb8fec9cf5b6293ac4329b3563f7ef6b91
--- /dev/null
+++ "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/BigDecimalExample.java"
@@ -0,0 +1,72 @@
+package com.java.minxi.java_20240516.java_2302_郑祺海_2344310215;
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Scanner;
+
+
+public class BigDecimalExample {
+    public static void main(String[] args) {
+// 创建BigDecimal对象
+        String numberAsString = "123.456";
+        BigDecimal bigDecimalNumber = new BigDecimal(numberAsString);
+        System.out.println("BigDecimal对象值为：" + bigDecimalNumber);
+
+// 执行加、减、乘、除运算
+        Scanner scanner = new Scanner(System.in);
+        BigDecimal num1 = new BigDecimal("10");
+        BigDecimal num2 = new BigDecimal("5");
+
+        System.out.println("输入计算方式");
+        String operator = scanner.next();
+
+        BigDecimal result = calculate(num1, num2, operator);
+        System.out.println("计算结果为：" + result);
+
+// 对BigDecimal对象执行舍入操作
+        BigDecimal originalNumber = new BigDecimal("123.456");
+        int scale = 2; // 精度
+        RoundingMode roundingMode = RoundingMode.HALF_UP; // 舍入模式
+        BigDecimal roundedNumber = originalNumber.setScale(scale, roundingMode);
+        System.out.println("舍入后的BigDecimal对象值为：" + roundedNumber);
+
+// 比较两个BigDecimal对象的值是否相等
+        BigDecimal num3 = new BigDecimal("1");
+        BigDecimal num4 = new BigDecimal("1");
+        System.out.println("两个BigDecimal对象是否相等：" + isEqual(num3, num4));
+
+// 比较两个BigDecimal对象的值大小
+        System.out.println("两个BigDecimal对象的大小关系：" + compareValues(num3, num4));
+    }
+
+    // 实现加、减、乘、除运算
+    public static BigDecimal calculate(BigDecimal num1, BigDecimal num2, String operator) {
+        BigDecimal result = BigDecimal.ZERO;
+        switch (operator) {
+            case "+":
+                result = num1.add(num2);
+                break;
+            case "-":
+                result = num1.subtract(num2);
+                break;
+            case "*":
+                result = num1.multiply(num2);
+                break;
+            case "/":
+                result = num1.divide(num2);
+                break;
+            default:
+                System.out.println("输入错误");
+        }
+        return result;
+    }
+
+    // 比较两个BigDecimal对象的值是否相等
+    public static boolean isEqual(BigDecimal num1, BigDecimal num2) {
+        return num1.equals(num2);
+    }
+
+    // 比较两个BigDecimal对象的值大小
+    public static int compareValues(BigDecimal num1, BigDecimal num2) {
+        return num1.compareTo(num2);
+    }
+}
diff --git "a/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/DateExample.java" "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/DateExample.java"
new file mode 100644
index 0000000000000000000000000000000000000000..957d613268cc3d18d7d0383d5d7b2114a24fb03e
--- /dev/null
+++ "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/DateExample.java"
@@ -0,0 +1,59 @@
+package com.java.minxi.java_20240516.java_2302_郑祺海_2344310215;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class DateExample {
+    public static void main(String[] args) {
+        //创建 Date 对象
+        Date currentDate = new Date();
+        System.out.println("当前时间：" + currentDate);
+
+        //获取 Date 对象的年份、月份、天数等
+        printDateInfo(currentDate);
+
+        //格式化 Date 对象
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+        String formattedDate = sdf.format(currentDate);
+        System.out.println("格式化后的日期：" + formattedDate);
+
+
+        //Date 转字符串再转回 Date
+        String dateStr = "2022-01-15 14:30:00";
+        Date parsedDate = parseDate(dateStr);
+        System.out.println("解析后的日期：" + parsedDate);
+
+        //System类使用
+        long currentTimeMillis = System.currentTimeMillis();
+        System.out.println("当前时间戳：" + currentTimeMillis);
+
+        Date systemDate = new Date(currentTimeMillis);
+        System.out.println("当前时间：" + sdf.format(systemDate));
+    }
+
+
+    //Date 对象的年份、月份、天数等
+    public static void printDateInfo(Date date) {
+        SimpleDateFormat sdf0 = new SimpleDateFormat("yyyy-MM-dd");
+        String[] dateInfo = sdf0.format(date).split("-");
+
+        int year = Integer.parseInt(dateInfo[0]);
+        int month = Integer.parseInt(dateInfo[1]);
+        int day = Integer.parseInt(dateInfo[2]);
+
+        System.out.println("年份：" + year);
+        System.out.println("月份：" + month);
+        System.out.println("天数：" + day);
+    }
+
+    // 将字符串解析为 Date 对象
+    public static Date parseDate(String dateStr) {
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+        try {
+            return sdf.parse(dateStr);
+        } catch (Exception e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+}
diff --git "a/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/MathExample.java" "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/MathExample.java"
new file mode 100644
index 0000000000000000000000000000000000000000..e48631476e8d6efd626c5672a2d2794b0a9d8f09
--- /dev/null
+++ "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/MathExample.java"
@@ -0,0 +1,50 @@
+package com.java.minxi.java_20240516.java_2302_郑祺海_2344310215;
+
+import java.util.Scanner;
+
+public class MathExample {
+    public static void main(String[] args) {
+        //绝对值
+        Scanner scanner = new Scanner(System.in);
+        System.out.println("请输入一个数字：");
+        double num = scanner.nextDouble();
+        double absNum = Math.abs(num);
+        System.out.println("绝对值为：" + absNum);
+
+        //最小值和最大值
+        int num1 = 5;
+        int num2 = 10;
+        int num3 = 3;
+
+        int min = Math.min(num1, Math.min(num2, num3));
+        int max = Math.max(num1, Math.max(num2, num3));
+
+        System.out.println("最小值为：" + min);
+        System.out.println("最大值为：" + max);
+
+        //四舍五入
+        System.out.println("请输入一个浮点数：");
+        double num4 = scanner.nextDouble();
+        long roundedNum = Math.round(num4);
+        System.out.println("四舍五入的整数为：" + roundedNum);
+
+        //随机数生成
+        System.out.println("请输入一个最大值：");
+        int maxValue = scanner.nextInt();
+        double randomNum = Math.random();
+        System.out.println("生成的随机数为：" + randomNum);
+        System.out.println("相乘后为" + randomNum * maxValue);
+
+        //计算平均值
+        int[] array = {5, 10, 15, 20, 25};
+        double sum = 0;
+
+        for (int num5 : array) {
+            sum += num5;
+        }
+
+        double average = sum / array.length;
+        System.out.println("平均值为：" + average);
+
+    }
+}
diff --git "a/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Person.java" "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Person.java"
new file mode 100644
index 0000000000000000000000000000000000000000..e2129c03c027b1a5f5473665c9892ba9f8798900
--- /dev/null
+++ "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/Person.java"
@@ -0,0 +1,49 @@
+package com.java.minxi.java_20240516.java_2302_郑祺海_2344310215;
+
+import java.util.Objects;
+
+public class Person {
+    //包含 `name` 和 `age` 属性
+    private String name;
+    private int age;
+
+    public Person(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    //
+    //重写 `toString` 方法，使其返回一个字符串，包含对象的 `name` 和 `age`。
+    @Override
+    public String toString() {
+        return "Name: " + name + ", Age: " + age;
+    }
+
+    //在 `Person` 类中重写 `equals` 方法，使得可以通过 `name` 和 `age` 属性比较两个 `Person` 对象是否相等。
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        Person person = (Person) obj;
+        return age == person.age && Objects.equals(name, person.name);
+    }
+
+
+
+}
diff --git "a/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/StringExample.java" "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/StringExample.java"
new file mode 100644
index 0000000000000000000000000000000000000000..685bfe6840c837b27d6babb1c6b90313e5c475ec
--- /dev/null
+++ "b/work/com/java/minxi/java_20240516/java_2302_\351\203\221\347\245\272\346\265\267_2344310215/StringExample.java"
@@ -0,0 +1,119 @@
+package com.java.minxi.java_20240516.java_2302_郑祺海_2344310215;
+
+public class StringExample {
+    public static void main(String[] args) {
+        // 1. 字符串连接
+        String str1 = "Hello, ";
+        String str2 = "World!";
+        String result1 = str1 + str2;
+        System.out.println("字符串连接结果：" + result1);
+
+        // 2. 字符串长度
+        String testStr = "Hello, World!";
+        int length = getStringLength(testStr);
+        System.out.println("字符串长度：" + length);
+
+        // 3. 字符串分割
+        String csvString = "apple,banana,orange";
+        String[] words = csvString.split(",");
+        System.out.println("字符串分割：");
+        for (String word : words) {
+            System.out.println(word);
+        }
+
+        // 4. 字符串反转
+        String trueStr = "Hello, World!";
+        String falshStr = reverseString(trueStr);
+        System.out.println("字符串反转：" + falshStr);
+
+        // 5. 字符串大小写转换
+        String mixedStr = "HeLLo, WoRLd!";
+        String lowerStr = mixedStr.toLowerCase();
+        String upperStr = mixedStr.toUpperCase();
+        System.out.println("小写字符串：" + lowerStr);
+        System.out.println("大写字符串：" + upperStr);
+
+        // 6. 字符串搜索
+        String searchStr = "Hello, World!";
+        boolean containsStr = searchStr.contains("World");
+        System.out.println("是否包含 'World'：" + containsStr);
+
+        // 7. 字符串替换
+        String originalString = "Hello, World!";
+        String replacedString = originalString.replace("World", "Java");
+        System.out.println("替换后的字符串：" + replacedString);
+
+        // 8. 字符串修剪
+        String oristr = "   Hello, World!   ";
+        String trimmedString = oristr.trim();
+        System.out.println("修剪后的字符串：" + trimmedString);
+
+        // 9. 字符串比较
+        String strA = "hello";
+        String strB = "Hello";
+        boolean equalsIgnoreCase = strA.equalsIgnoreCase(strB);
+        System.out.println("忽略大小写是否相等：" + equalsIgnoreCase);
+
+        // 其余实现方法请在下面继续...
+
+        // 10. 子串操作
+        String sourceStr = "Hello, World!";
+        String subString = getSubstring(sourceStr, 7, 12);
+        System.out.println("子串：" + subString);
+
+        // 11. 字符串结束符检查
+        String checkStr1 = "Hello, World!";
+        boolean endsWith1 = checkStr1.endsWith("!");
+        System.out.println("是否以 '!' 结尾：" + endsWith1);
+
+        // 12. 字符串开始符检查
+        String checkStr2 = "Hello, World!";
+        boolean startsWith = checkStr2.startsWith("Hello");
+        System.out.println("是否以 'Hello' 开始：" + startsWith);
+
+        // 13. 字符串中字符的出现次数
+        String countStr = "Hello, World!";
+        char charToCount = 'l';
+        int charCount = countCharOccurrences(countStr, charToCount);
+        System.out.println("字符 'l' 出现次数：" + charCount);
+
+        // 14. 字符串与数字的转换
+        String numStr = "123";
+        int numInt = Integer.parseInt(numStr);
+        System.out.println("转换为整数：" + numInt);
+
+        // 15. StringBuilder拼接
+        String strConst1 = "Hello, ";
+        String strConst2 = "World!";
+        String strConst3 = "Nice to meet you!";
+        StringBuilder sb = new StringBuilder();
+        sb.append(strConst1).append(strConst2).append(strConst3);
+        System.out.println("StringBuilder拼接结果：" + sb.toString());
+    }
+
+    // 获取字符串长度
+    public static int getStringLength(String str) {
+        return str.length();
+    }
+
+    // 字符串反转
+    public static String reverseString(String str) {
+        return new StringBuilder(str).reverse().toString();
+    }
+
+    // 提取子串
+    public static String getSubstring(String str, int startIndex, int endIndex) {
+        return str.substring(startIndex, endIndex);
+    }
+
+    // 统计字符出现次数
+    public static int countCharOccurrences(String str, char ch) {
+        int count = 0;
+        for (int i = 0; i < str.length(); i++) {
+            if (str.charAt(i) == ch) {
+                count++;
+            }
+        }
+        return count;
+    }
+}