diff --git a/com/study/demo3/Bicycle.java b/com/study/demo3/Bicycle.java
index 5a2d76a..a3d9709 100644
--- a/com/study/demo3/Bicycle.java
+++ b/com/study/demo3/Bicycle.java
@@ -1,7 +1,8 @@
 package com.study.demo3;
+
 public class Bicycle extends Vehicle {
-    @Override
-    public void start() {
-        System.out.println("The bike is started");
-    }
+  @Override
+  public void start() {
+    System.out.println("The bike is started");
+  }
 }
diff --git a/com/study/demo3/Book.java b/com/study/demo3/Book.java
index bcb0cc2..a4646f1 100644
--- a/com/study/demo3/Book.java
+++ b/com/study/demo3/Book.java
@@ -1,61 +1,57 @@
 package com.study.demo3;
 
 public class Book {
-    protected String isbn;
-    protected String title;
-    protected boolean available;
+  protected String isbn;
+  protected String title;
+  protected boolean available;
 
-   
-    public Book() {
-        this.available = true;
-    }
+  public Book() {
+    this.available = true;
+  }
 
-   
-    public Book(String isbn, String title) {
-        this.isbn = isbn;
-        this.title = title;
-        this.available = true;
-    }
+  public Book(String isbn, String title) {
+    this.isbn = isbn;
+    this.title = title;
+    this.available = true;
+  }
 
-   
-    public Book(String isbn, String title, boolean available) {
-        this.isbn = isbn;
-        this.title = title;
-        this.available = available;
-    }
+  public Book(String isbn, String title, boolean available) {
+    this.isbn = isbn;
+    this.title = title;
+    this.available = available;
+  }
 
-   
-    public String getIsbn() {
-        return isbn;
-    }
+  public String getIsbn() {
+    return isbn;
+  }
 
-    public void setIsbn(String isbn) {
-        this.isbn = isbn;
-    }
+  public void setIsbn(String isbn) {
+    this.isbn = isbn;
+  }
 
-    public String getTitle() {
-        return title;
-    }
+  public String getTitle() {
+    return title;
+  }
 
-    public void setTitle(String title) {
-        this.title = title;
-    }
+  public void setTitle(String title) {
+    this.title = title;
+  }
 
-    public boolean isAvailable() {
-        return available;
-    }
+  public boolean isAvailable() {
+    return available;
+  }
 
-    public void setAvailable(boolean available) {
-        this.available = available;
-    }
+  public void setAvailable(boolean available) {
+    this.available = available;
+  }
 
-   
-    public void returnBook() {
-        if (!this.available) {
-            this.available = true;
-            System.out.println(this.title + " (ISBN: " + this.isbn + ") has been returned and is now available.");
-        } else {
-            System.out.println(this.title + " (ISBN: " + this.isbn + ") is already available.");
-        }
+  public void returnBook() {
+    if (!this.available) {
+      this.available = true;
+      System.out.println(
+          this.title + " (ISBN: " + this.isbn + ") has been returned and is now available.");
+    } else {
+      System.out.println(this.title + " (ISBN: " + this.isbn + ") is already available.");
     }
+  }
 }
diff --git a/com/study/demo3/Car.java b/com/study/demo3/Car.java
index 91dc698..db95f60 100644
--- a/com/study/demo3/Car.java
+++ b/com/study/demo3/Car.java
@@ -1,8 +1,8 @@
 package com.study.demo3;
+
 public class Car extends Vehicle {
-    @Override
-   
-    public void start() {
-        System.out.println("The car is started");
-    }
+  @Override
+  public void start() {
+    System.out.println("The car is started");
+  }
 }
diff --git a/com/study/demo3/EBook.java b/com/study/demo3/EBook.java
index ccbac3f..23148bd 100644
--- a/com/study/demo3/EBook.java
+++ b/com/study/demo3/EBook.java
@@ -1,30 +1,35 @@
 package com.study.demo3;
+
 public class EBook extends Book {
-    private double fileSize;
+  private double fileSize;
 
-   
-    public EBook() {
-        super();
-    }
+  public EBook() {
+    super();
+  }
 
-   
-   
-    public EBook(String isbn, String title, double fileSize) {
-        super(isbn, title);
-        this.fileSize = fileSize;
-    }
+  public EBook(String isbn, String title, double fileSize) {
+    super(isbn, title);
+    this.fileSize = fileSize;
+  }
 
-   
-    public double getFileSize() {
-        return fileSize;
-    }
+  public double getFileSize() {
+    return fileSize;
+  }
 
-    public void setFileSize(double fileSize) {
-        this.fileSize = fileSize;
-    }
+  public void setFileSize(double fileSize) {
+    this.fileSize = fileSize;
+  }
 
-    @Override
-    public String toString() {
-        return "EBook [ISBN=" + isbn + ", Title=" + title + ", FileSize=" + fileSize + "MB, Available=" + available + "]";
-    }
+  @Override
+  public String toString() {
+    return "EBook [ISBN="
+        + isbn
+        + ", Title="
+        + title
+        + ", FileSize="
+        + fileSize
+        + "MB, Available="
+        + available
+        + "]";
+  }
 }
diff --git a/com/study/demo3/Library.java b/com/study/demo3/Library.java
index b64d39c..8c55b26 100644
--- a/com/study/demo3/Library.java
+++ b/com/study/demo3/Library.java
@@ -1,42 +1,37 @@
 package com.study.demo3;
+
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.ArrayList;
 
 public class Library {
-   
-    private Map<String, Book> books;
 
-    public Library() {
-        this.books = new HashMap<>();
+  private Map<String, Book> books;
+
+  public Library() {
+    this.books = new HashMap<>();
+  }
+
+  public void addBook(Book b) {
+    String isbn = b.getIsbn();
+
+    if (books.containsKey(isbn)) {
+      System.out.println("The book already exists, adding it failed.");
+    } else {
+      books.put(isbn, b);
+      System.out.println("Book added successfully: " + b.getTitle());
     }
+  }
 
-   
-   
-    public void addBook(Book b) {
-        String isbn = b.getIsbn();
+  public List<Book> searchAvailableBooks() {
+    List<Book> availableBooks = new ArrayList<>();
 
-       
-        if (books.containsKey(isbn)) {
-            System.out.println("The book already exists, adding it failed.");
-        } else {
-            books.put(isbn, b);
-            System.out.println("Book added successfully: " + b.getTitle());
-        }
-    }
-
-   
-   
-    public List<Book> searchAvailableBooks() {
-        List<Book> availableBooks = new ArrayList<>();
-        
-       
-        for (Book book : books.values()) {
-            if (book.isAvailable()) {
-                availableBooks.add(book);
-            }
-        }
-        return availableBooks;
+    for (Book book : books.values()) {
+      if (book.isAvailable()) {
+        availableBooks.add(book);
+      }
     }
+    return availableBooks;
+  }
 }
diff --git a/com/study/demo3/LibraryTest.java b/com/study/demo3/LibraryTest.java
index 46baa61..d2294d7 100644
--- a/com/study/demo3/LibraryTest.java
+++ b/com/study/demo3/LibraryTest.java
@@ -1,44 +1,39 @@
 package com.study.demo3;
+
 import java.util.List;
 
 public class LibraryTest {
-    public static void main(String[] args) {
-        Library lib = new Library();
+  public static void main(String[] args) {
+    Library lib = new Library();
 
-       
-        EBook e1 = new EBook("E001", "Java Basics", 5.2);
-       
-        e1.setAvailable(false); 
+    EBook e1 = new EBook("E001", "Java Basics", 5.2);
 
-       
-        PrintedBook p1 = new PrintedBook("P001", "Design Patterns", 3);
+    e1.setAvailable(false);
 
-       
-        lib.addBook(e1);
-        lib.addBook(p1);
+    PrintedBook p1 = new PrintedBook("P001", "Design Patterns", 3);
 
-       
-        lib.addBook(p1);
+    lib.addBook(e1);
+    lib.addBook(p1);
 
-       
-        System.out.println("\n--- 可借阅图书列表 (available = true) ---");
-        List<Book> availableList = lib.searchAvailableBooks();
+    lib.addBook(p1);
 
-        if (availableList.isEmpty()) {
-            System.out.println("No books are currently available for loan.");
-        } else {
-            for (Book book : availableList) {
-               
-                System.out.println("- " + book.getTitle() + " (ISBN: " + book.getIsbn() + ")");
-            }
-        }
-        
-       
-        e1.returnBook(); 
-        System.out.println("\n--- 恢复 e1 后可借阅图书列表 ---");
-        availableList = lib.searchAvailableBooks();
-        for (Book book : availableList) {
-            System.out.println("- " + book.getTitle() + " (ISBN: " + book.getIsbn() + ")");
-        }
+    System.out.println("\n--- 可借阅图书列表 (available = true) ---");
+    List<Book> availableList = lib.searchAvailableBooks();
+
+    if (availableList.isEmpty()) {
+      System.out.println("No books are currently available for loan.");
+    } else {
+      for (Book book : availableList) {
+
+        System.out.println("- " + book.getTitle() + " (ISBN: " + book.getIsbn() + ")");
+      }
     }
+
+    e1.returnBook();
+    System.out.println("\n--- 恢复 e1 后可借阅图书列表 ---");
+    availableList = lib.searchAvailableBooks();
+    for (Book book : availableList) {
+      System.out.println("- " + book.getTitle() + " (ISBN: " + book.getIsbn() + ")");
+    }
+  }
 }
diff --git a/com/study/demo3/Main3.java b/com/study/demo3/Main3.java
index 1d41593..ac1a952 100644
--- a/com/study/demo3/Main3.java
+++ b/com/study/demo3/Main3.java
@@ -1,34 +1,30 @@
 package com.study.demo3;
+
 public class Main {
-    public static void main(String[] args) {
-       
-        System.out.println("--- 测试 EBook ---");
-       
-        EBook ebook = new EBook("123-456", "Java Programming", 2.5);
-        System.out.println("EBook Status (Initial): " + ebook.toString());
+  public static void main(String[] args) {
 
-       
-        ebook.setAvailable(false);
-        System.out.println("EBook Status (Borrowed): " + ebook.toString());
+    System.out.println("--- 测试 EBook ---");
 
-       
-        ebook.returnBook();
-        System.out.println("EBook Status (After Return): " + ebook.toString());
+    EBook ebook = new EBook("123-456", "Java Programming", 2.5);
+    System.out.println("EBook Status (Initial): " + ebook.toString());
 
-       
-        System.out.println("\n--- 测试 PrintedBook ---");
-        PrintedBook pbook = new PrintedBook();
-        pbook.setIsbn("789-012");
-        pbook.setTitle("Python Guide");
-        pbook.setStock(10);
-        System.out.println("PBook Status (Initial): " + pbook.toString());
+    ebook.setAvailable(false);
+    System.out.println("EBook Status (Borrowed): " + ebook.toString());
 
-       
-        pbook.setAvailable(false);
-        System.out.println("PBook Status (Borrowed): " + pbook.toString());
+    ebook.returnBook();
+    System.out.println("EBook Status (After Return): " + ebook.toString());
 
-       
-        pbook.returnBook();
-        System.out.println("PBook Status (After Return): " + pbook.toString());
-    }
+    System.out.println("\n--- 测试 PrintedBook ---");
+    PrintedBook pbook = new PrintedBook();
+    pbook.setIsbn("789-012");
+    pbook.setTitle("Python Guide");
+    pbook.setStock(10);
+    System.out.println("PBook Status (Initial): " + pbook.toString());
+
+    pbook.setAvailable(false);
+    System.out.println("PBook Status (Borrowed): " + pbook.toString());
+
+    pbook.returnBook();
+    System.out.println("PBook Status (After Return): " + pbook.toString());
+  }
 }
diff --git a/com/study/demo3/PrintedBook.java b/com/study/demo3/PrintedBook.java
index 18f9be1..02b0750 100644
--- a/com/study/demo3/PrintedBook.java
+++ b/com/study/demo3/PrintedBook.java
@@ -1,29 +1,35 @@
 package com.study.demo3;
+
 public class PrintedBook extends Book {
-    private int stock;
+  private int stock;
 
-   
-    public PrintedBook() {
-        super();
-    }
+  public PrintedBook() {
+    super();
+  }
 
-   
-    public PrintedBook(String isbn, String title, int stock) {
-        super(isbn, title);
-        this.stock = stock;
-    }
+  public PrintedBook(String isbn, String title, int stock) {
+    super(isbn, title);
+    this.stock = stock;
+  }
 
-   
-    public int getStock() {
-        return stock;
-    }
+  public int getStock() {
+    return stock;
+  }
 
-    public void setStock(int stock) {
-        this.stock = stock;
-    }
+  public void setStock(int stock) {
+    this.stock = stock;
+  }
 
-    @Override
-    public String toString() {
-        return "PrintedBook [ISBN=" + isbn + ", Title=" + title + ", Stock=" + stock + ", Available=" + available + "]";
-    }
+  @Override
+  public String toString() {
+    return "PrintedBook [ISBN="
+        + isbn
+        + ", Title="
+        + title
+        + ", Stock="
+        + stock
+        + ", Available="
+        + available
+        + "]";
+  }
 }
diff --git a/com/study/demo3/StudentManager.java b/com/study/demo3/StudentManager.java
index be20826..22d44ee 100644
--- a/com/study/demo3/StudentManager.java
+++ b/com/study/demo3/StudentManager.java
@@ -1,28 +1,29 @@
 package com.study.demo3;
+
 import java.util.*;
 
 public class StudentManager {
-    public static void main(String[] args) {
-        List<String> studentNames = new ArrayList<>();
-        Map<String, Integer> studentScores = new HashMap<>();
+  public static void main(String[] args) {
+    List<String> studentNames = new ArrayList<>();
+    Map<String, Integer> studentScores = new HashMap<>();
 
-        studentNames.add("张三");
-        studentNames.add("李四");
-        studentNames.add("王五");
+    studentNames.add("张三");
+    studentNames.add("李四");
+    studentNames.add("王五");
 
-        studentScores.put("张三", 85);
-        studentScores.put("李四", 77);
-        studentScores.put("王五", 99);
+    studentScores.put("张三", 85);
+    studentScores.put("李四", 77);
+    studentScores.put("王五", 99);
 
-        System.out.println("--- 所有学生姓名 ---");
-        for (String name : studentNames) {
-            System.out.println(name);
-        }
-
-        studentScores.put("张三", 70);
-
-        Integer zhangsanScore = studentScores.get("张三");
-        System.out.println("\n--- 修改后张三的成绩 ---");
-        System.out.println("张三的成绩: " + zhangsanScore);
+    System.out.println("--- 所有学生姓名 ---");
+    for (String name : studentNames) {
+      System.out.println(name);
     }
+
+    studentScores.put("张三", 70);
+
+    Integer zhangsanScore = studentScores.get("张三");
+    System.out.println("\n--- 修改后张三的成绩 ---");
+    System.out.println("张三的成绩: " + zhangsanScore);
+  }
 }
diff --git a/com/study/demo3/Train.java b/com/study/demo3/Train.java
index d99c2ff..5585c90 100644
--- a/com/study/demo3/Train.java
+++ b/com/study/demo3/Train.java
@@ -1,7 +1,8 @@
 package com.study.demo3;
+
 public class Train extends Vehicle {
-    @Override
-    public void start() {
-        System.out.println("The train is started");
-    }
+  @Override
+  public void start() {
+    System.out.println("The train is started");
+  }
 }
diff --git a/com/study/demo3/Vehicle.java b/com/study/demo3/Vehicle.java
index 7d86d57..d3ec5f8 100644
--- a/com/study/demo3/Vehicle.java
+++ b/com/study/demo3/Vehicle.java
@@ -1,20 +1,21 @@
 package com.study.demo3;
+
 public class Vehicle {
-    protected String name;
+  protected String name;
 
-    public Vehicle(String name) {
-        this.name = name;
-    }
-    
-    public Vehicle() {
-        this.name = "Unknown Vehicle";
-    }
+  public Vehicle(String name) {
+    this.name = name;
+  }
 
-    public void start() {
-        System.out.println("Vehicle Start");
-    }
+  public Vehicle() {
+    this.name = "Unknown Vehicle";
+  }
 
-    public void stop() {
-        System.out.println("Vehicle Stop");
-    }
+  public void start() {
+    System.out.println("Vehicle Start");
+  }
+
+  public void stop() {
+    System.out.println("Vehicle Stop");
+  }
 }