diff --git a/Java/Java源代码/jdk21demo/VirtualThreadTest.java b/Java/Java源代码/jdk21demo/VirtualThreadTest.java
new file mode 100644
index 00000000..7465129b
--- /dev/null
+++ b/Java/Java源代码/jdk21demo/VirtualThreadTest.java
@@ -0,0 +1,25 @@
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+public class VirtualThreadTest {
+    public static void main(String[] args) {
+        // long start = System.currentTimeMillis();
+        // try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) {
+        try (ExecutorService executor = Executors.newFixedThreadPool(10)) {
+            for (int i = 0; i < 1000; i++) {
+                final int index = i;
+                executor.submit(() -> {
+                    try {
+                        Thread.sleep(1000);
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                    }
+                    Thread.sleep(1000);
+                    System.out.println(Thread.currentThread().getName() + ": " + index + " is running");
+                });
+            }
+        }
+        // long end = System.currentTimeMillis();
+        // System.out.println("Total time: " + (end - start) + " ms");
+    }
+}
diff --git a/JavaDemo/JdkDemo/DynamicProxy/pom.xml b/JavaDemo/jdk-demo/DynamicProxy/pom.xml
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/pom.xml
rename to JavaDemo/jdk-demo/DynamicProxy/pom.xml
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/CglibDynamicProxy.java b/JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/CglibDynamicProxy.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/CglibDynamicProxy.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/CglibDynamicProxy.java
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/DynamicProxy.java b/JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/DynamicProxy.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/DynamicProxy.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/DynamicProxy.java
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogHandler.java b/JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogHandler.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogHandler.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogHandler.java
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogInterceptor.java b/JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogInterceptor.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogInterceptor.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/handler/LogInterceptor.java
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserService.java b/JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserService.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserService.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserService.java
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserServiceImpl.java b/JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserServiceImpl.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserServiceImpl.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/main/java/com/ykl/proxy/service/UserServiceImpl.java
diff --git a/JavaDemo/JdkDemo/DynamicProxy/src/test/java/org/example/AppTest.java b/JavaDemo/jdk-demo/DynamicProxy/src/test/java/org/example/AppTest.java
similarity index 100%
rename from JavaDemo/JdkDemo/DynamicProxy/src/test/java/org/example/AppTest.java
rename to JavaDemo/jdk-demo/DynamicProxy/src/test/java/org/example/AppTest.java
diff --git a/JavaDemo/JdkDemo/pom.xml b/JavaDemo/jdk-demo/pom.xml
similarity index 100%
rename from JavaDemo/JdkDemo/pom.xml
rename to JavaDemo/jdk-demo/pom.xml
diff --git a/JavaDemo/JdkDemo/src/main/java/org/example/App.java b/JavaDemo/jdk-demo/src/main/java/org/example/App.java
similarity index 100%
rename from JavaDemo/JdkDemo/src/main/java/org/example/App.java
rename to JavaDemo/jdk-demo/src/main/java/org/example/App.java
diff --git a/JavaDemo/JdkDemo/src/test/java/org/example/AppTest.java b/JavaDemo/jdk-demo/src/test/java/org/example/AppTest.java
similarity index 100%
rename from JavaDemo/JdkDemo/src/test/java/org/example/AppTest.java
rename to JavaDemo/jdk-demo/src/test/java/org/example/AppTest.java
diff --git a/JavaDemo/multiclass-demo/Makefile b/JavaDemo/multiclass-demo/Makefile
new file mode 100644
index 00000000..84677c64
--- /dev/null
+++ b/JavaDemo/multiclass-demo/Makefile
@@ -0,0 +1,54 @@
+# Makefile for multiclass-demo Java project
+
+# Java compiler and options
+JAVAC = javac
+JAVA = java
+JFLAGS = -g
+
+# Source and build directories
+SRC_DIR = src
+BUILD_DIR = build
+
+# Find all Java source files
+SOURCES = $(shell find $(SRC_DIR) -name "*.java")
+CLASSES = $(SOURCES:$(SRC_DIR)/%.java=$(BUILD_DIR)/%.class)
+
+# Main class
+MAIN_CLASS = com.example.Application
+
+# Default target
+.PHONY: all
+all: compile
+
+# Compile all Java source files
+.PHONY: compile
+compile:
+	@mkdir -p $(BUILD_DIR)
+	$(JAVAC) $(JFLAGS) -sourcepath $(SRC_DIR) -d $(BUILD_DIR) $(SOURCES)
+	@echo "Compilation completed successfully!"
+
+# Run the application
+.PHONY: run
+run: compile
+	$(JAVA) -cp $(BUILD_DIR) $(MAIN_CLASS)
+
+# Clean compiled classes
+.PHONY: clean
+clean:
+	rm -rf $(BUILD_DIR)/*
+	@echo "Clean completed!"
+
+# Rebuild the project
+.PHONY: rebuild
+rebuild: clean compile
+
+# Help target
+.PHONY: help
+help:
+	@echo "Available targets:"
+	@echo "  all      - Compile all source files (default)"
+	@echo "  compile  - Compile all source files"
+	@echo "  run      - Compile and run the application"
+	@echo "  clean    - Remove all compiled classes"
+	@echo "  rebuild  - Clean and compile all source files"
+	@echo "  help     - Display this help message"
\ No newline at end of file
diff --git a/JavaDemo/multiclass-demo/src/com/example/Application.java b/JavaDemo/multiclass-demo/src/com/example/Application.java
new file mode 100644
index 00000000..fd55c916
--- /dev/null
+++ b/JavaDemo/multiclass-demo/src/com/example/Application.java
@@ -0,0 +1,29 @@
+package com.example;
+
+public class Application {
+    public static void main(String[] args) {
+        // 创建PersonService实例
+        PersonService service = new PersonService();
+        
+        // 添加一些Person对象，注意名字的大小写会被自动规范化
+        service.addPerson(new Person("alice", 25));
+        service.addPerson(new Person("BOB", 30));
+        service.addPerson(new Person("cHaRlIe", 35));
+        
+        // 显示所有人员
+        System.out.println("All persons (with names properly capitalized):");
+        for (Person person : service.getAllPersons()) {
+            System.out.println(person);
+        }
+        
+        // 查找特定人员
+        Person found = service.findPersonByName("Bob");
+        System.out.println("\nFound person: " + found);
+        
+        // 测试修改人员名字
+        if (found != null) {
+            found.setName("david");
+            System.out.println("After name change: " + found);
+        }
+    }
+}
\ No newline at end of file
diff --git a/JavaDemo/multiclass-demo/src/com/example/Person.java b/JavaDemo/multiclass-demo/src/com/example/Person.java
new file mode 100644
index 00000000..1f0fc046
--- /dev/null
+++ b/JavaDemo/multiclass-demo/src/com/example/Person.java
@@ -0,0 +1,35 @@
+package com.example;
+
+import com.example.util.StringUtils;
+
+public class Person {
+    private String name;
+    private int age;
+    
+    public Person(String name, int age) {
+        // 使用工具类方法
+        this.name = StringUtils.capitalize(name);
+        this.age = age;
+    }
+    
+    public String getName() {
+        return name;
+    }
+    
+    public int getAge() {
+        return age;
+    }
+    
+    public void setName(String name) {
+        this.name = StringUtils.capitalize(name);
+    }
+    
+    public void setAge(int age) {
+        this.age = age;
+    }
+    
+    @Override
+    public String toString() {
+        return "Person{name='" + name + "', age=" + age + "}";
+    }
+}
\ No newline at end of file
diff --git a/JavaDemo/multiclass-demo/src/com/example/PersonService.java b/JavaDemo/multiclass-demo/src/com/example/PersonService.java
new file mode 100644
index 00000000..009e8cf2
--- /dev/null
+++ b/JavaDemo/multiclass-demo/src/com/example/PersonService.java
@@ -0,0 +1,27 @@
+package com.example;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PersonService {
+    private List<Person> persons;
+    
+    public PersonService() {
+        this.persons = new ArrayList<>();
+    }
+    
+    public void addPerson(Person person) {
+        persons.add(person);
+    }
+    
+    public List<Person> getAllPersons() {
+        return new ArrayList<>(persons);
+    }
+    
+    public Person findPersonByName(String name) {
+        return persons.stream()
+                .filter(p -> p.getName().equals(name))
+                .findFirst()
+                .orElse(null);
+    }
+}
\ No newline at end of file
diff --git a/JavaDemo/multiclass-demo/src/com/example/util/StringUtils.java b/JavaDemo/multiclass-demo/src/com/example/util/StringUtils.java
new file mode 100644
index 00000000..6dac1ee7
--- /dev/null
+++ b/JavaDemo/multiclass-demo/src/com/example/util/StringUtils.java
@@ -0,0 +1,14 @@
+package com.example.util;
+
+public class StringUtils {
+    public static boolean isEmpty(String str) {
+        return str == null || str.length() == 0;
+    }
+    
+    public static String capitalize(String str) {
+        if (isEmpty(str)) {
+            return str;
+        }
+        return str.substring(0, 1).toUpperCase() + str.substring(1).toLowerCase();
+    }
+}
\ No newline at end of file
diff --git a/算法/A类：基本算法/3.9 位运算算法.md b/算法/A类：基本算法/3.9 位运算算法.md
index f26b844c..656495a4 100644
--- a/算法/A类：基本算法/3.9 位运算算法.md	
+++ b/算法/A类：基本算法/3.9 位运算算法.md	
@@ -39,7 +39,8 @@ double myPow(double x, int n) {
     double result=1;
     double temp=x;
     while(N!=0){
-        if( N & 1)result=result*temp;
+        if( N & 1)
+            result=result*temp;
         temp *=temp;
         N= N>>1;
     }