diff --git a/.DS_Store b/.DS_Store
index 613a81f..b9c248e 100644
Binary files a/.DS_Store and b/.DS_Store differ
diff --git a/src/.DS_Store b/src/.DS_Store
index 5008ddf..66b715a 100644
Binary files a/src/.DS_Store and b/src/.DS_Store differ
diff --git a/src/Generator.java b/src/Generator.java
index 50b26bd..a786087 100644
--- a/src/Generator.java
+++ b/src/Generator.java
@@ -1,166 +1,195 @@
-import java.util.*;
+import java.util.Random;
+import java.util.Set;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.stream.Collectors;
 
+/**
+ * 工具类：负责生成不同难度的数学题目。
+ */
 public class Generator {
-    private static final Random rand = new Random();
 
-    static class QuestionGenerator {
-        private final Login.Level level;
-        private final Set<String> existing;
+  private static final Random RAND = new Random();
+  private static final int MAX_ATTEMPTS = 2000;
 
-        QuestionGenerator(Login.Level level, List<String> existingQuestions) {
-            this.level = level;
-            this.existing = existingQuestions.stream().map(String::trim).collect(Collectors.toSet());
-        }
+  /**
+   * 内部类：按用户难度等级生成题目。
+   */
+  static class QuestionGenerator {
 
-        List<String> generatePaper(int n) {
-            Set<String> generated = new LinkedHashSet<>();
-            // 防止死循环
-            int attempts = 0;
-            int maxAttempts = 2000;
-
-            while (generated.size() < n && attempts < maxAttempts) {
-                attempts++;
-                String q = generateOneQuestion();
-                // 统一去掉题号与多余空白来比对
-                String key = normalize(q);
-                //与文件内+本次前面生成的查重
-                if (!existing.contains(key) && !generated.contains(key)) {
-                    generated.add(q);
-                }
-            }
-            if (generated.size() < n) {
-                System.out.println("注意：无法生成足够的不重复题目，已生成 " + generated.size() + " 道题（请求 " + n + " 道）");
-            }
-            return new ArrayList<>(generated);
-        }
-        //去空格
-        private String normalize(String s) {
-            return s.replaceAll("\\s+","").toLowerCase();
-        }
+    private final Login.Level level;
+    private final Set<String> existing;
 
-        // 生成单题主逻辑
-        private String generateOneQuestion() {
-            int operands = rand.nextInt(5) + 1; // 保证 2..5 个操作数
-            return switch (level) {
-                case PRIMARY -> genPrimary(operands);
-                case MIDDLE -> genMiddle(operands);
-                case HIGH -> genHigh(operands);
-            };
-        }
-        // 生成小学题（只有 + - * / 和括号）
-        private String genPrimary(int operands) {
-            if (operands == 1) {
-                return String.valueOf(randInt(1,100));
-            }
-            List<String> ops = Arrays.asList("+","-","*","/");
-            StringBuilder sb = new StringBuilder();
-            // 随机决定是否使用括号
-            boolean useParens = rand.nextBoolean();
-            if (useParens && operands >= 3 && rand.nextBoolean()) {
-                // 构造 (a op b) op c ...
-                sb.append("(");
-                sb.append(randInt(1,100)).append(" ").append(randomChoice(ops)).append(" ").append(randInt(1,100));
-                sb.append(")");
-                for (int i=2;i<operands;i++) {
-                    sb.append(" ").append(randomChoice(ops)).append(" ").append(randInt(1,100));
-                }
-            } else {
-                // 直连
-                sb.append(randInt(1,100));
-                for (int i=1;i<operands;i++) {
-                    sb.append(" ").append(randomChoice(ops)).append(" ").append(randInt(1,100));
-                }
-            }
-            return sb.toString();
-        }
+    QuestionGenerator(Login.Level level, List<String> existingQuestions) {
+      this.level = level;
+      this.existing = existingQuestions.stream().map(String::trim).collect(Collectors.toSet());
+    }
 
-        // 生成初中题：至少包含一个 ^2 或 sqrt()
-        private String genMiddle(int operands) {
-            // 基本表达式生成，后插入平方或开根号
-            String expr = genPrimary(operands); // 基本算术
-            // 2选1
-            if (rand.nextBoolean()) {
-                // 找一个数字位置并替换为 (x)^2
-                expr = applySquare(expr);
-            } else {
-                expr = applySqrt(expr);
-            }
-            return expr;
-        }
+    /**
+     * 生成一份试卷。
+     *
+     * @param n 需要生成的题目数量
+     * @return 生成的题目列表
+     */
+    List<String> generatePaper(int n) {
+      Set<String> generated = new LinkedHashSet<>();
+      // 防止死循环
+      int attempts = 0;
 
-        // 生成高中题：至少包含 sin/cos/tan
-        private String genHigh(int operands) {
-            String expr = genPrimary(operands);
-            expr = applyTrig(expr);
-            return expr;
+      while (generated.size() < n && attempts < MAX_ATTEMPTS) {
+        attempts++;
+        String q = generateOneQuestion();
+        // 统一去掉题号与多余空白来比对
+        String key = normalize(q);
+        //与文件内+本次前面生成的查重
+        if (!existing.contains(key) && !generated.contains(key)) {
+          generated.add(q);
         }
+      }
 
-        // 把表达式中某个数字替换为 (x)^2
-        private String applySquare(String expr) {
-            // 寻找所有数字的片段
-            List<int[]> spans = findNumberSpans(expr);
-            if (spans.isEmpty()) {
-                return expr + "^2";
-            }
-            int[] s = spans.get(rand.nextInt(spans.size()));
-            String before = expr.substring(0, s[0]);
-            String num = expr.substring(s[0], s[1]);
-            String after = expr.substring(s[1]);
-            return before + "(" + num + ")^2" + after;
-        }
+      if (generated.size() < n) {
+        System.out.println(
+            "注意：无法生成足够的不重复题目，已生成 "
+                + generated.size() + " 道题（请求 " + n + " 道）");
+      }
+      return new ArrayList<>(generated);
+    }
 
-        // 把表达式中某个数字替换为 sqrt(x)
-        private String applySqrt(String expr) {
-            List<int[]> spans = findNumberSpans(expr);
-            if (spans.isEmpty()) {
-                return "sqrt(" + expr + ")";
-            }
-            int[] s = spans.get(rand.nextInt(spans.size()));
-            String before = expr.substring(0, s[0]);
-            String num = expr.substring(s[0], s[1]);
-            String after = expr.substring(s[1]);
-            return before + "sqrt(" + num + ")" + after;
-        }
+    //去空格
+    private String normalize(String s) {
+      return s.replaceAll("\\s+", "").toLowerCase();
+    }
 
-        // 把某个数字或子表达式替换为 sin(x)/cos(x)/tan(x)
-        private String applyTrig(String expr) {
-            List<int[]> spans = findNumberSpans(expr);
-            String func = randomChoice(Arrays.asList("sin","cos","tan"));
-            if (spans.isEmpty()) {
-                return func + "(" + expr + ")";
-            }
-            int[] s = spans.get(rand.nextInt(spans.size()));
-            String before = expr.substring(0, s[0]);
-            String num = expr.substring(s[0], s[1]);
-            String after = expr.substring(s[1]);
-            return before + func + "(" + num + ")" + after;
-        }
+    // 生成单题主逻辑
+    private String generateOneQuestion() {
+      int operands = RAND.nextInt(5) + 1; // 保证 2..5 个操作数
+      return switch (level) {
+        case PRIMARY -> genPrimary(operands);
+        case MIDDLE -> genMiddle(operands);
+        case HIGH -> genHigh(operands);
+      };
+    }
 
-        // 找出数字位置
-        private List<int[]> findNumberSpans(String expr) {
-            List<int[]> spans = new ArrayList<>();
-            char[] chs = expr.toCharArray();
-            int i = 0, n = chs.length;
-            while (i < n) {
-                if (Character.isDigit(chs[i])) {
-                    int j = i;
-                    while (j < n && (Character.isDigit(chs[j]) )) j++;
-                    spans.add(new int[]{i, j});
-                    i = j;
-                } else {
-                    i++;
-                }
-            }
-            return spans;
+    // 生成小学题（只有 + - * / 和括号）
+    private String genPrimary(int operands) {
+      if (operands == 1) {
+        return String.valueOf(randInt(1, 100));
+      }
+      List<String> ops = Arrays.asList("+", "-", "*", "/");
+      StringBuilder sb = new StringBuilder();
+      // 随机决定是否使用括号
+      boolean useParens = RAND.nextBoolean();
+      if (useParens && operands >= 3 && RAND.nextBoolean()) {
+        // 构造 (a op b) op c ...
+        sb.append("(");
+        sb.append(randInt(1, 100)).append(" ").append(randomChoice(ops)).append(" ")
+            .append(randInt(1, 100));
+        sb.append(")");
+        for (int i = 2; i < operands; i++) {
+          sb.append(" ").append(randomChoice(ops)).append(" ").append(randInt(1, 100));
         }
-        //a..b随机数
-        private int randInt(int a, int b) {
-            return rand.nextInt(b - a + 1) + a;
+      } else {
+        // 直连
+        sb.append(randInt(1, 100));
+        for (int i = 1; i < operands; i++) {
+          sb.append(" ").append(randomChoice(ops)).append(" ").append(randInt(1, 100));
         }
-        //抽签功能
-        private <T> T randomChoice(List<T> list) {
-            return list.get(rand.nextInt(list.size()));
+      }
+      return sb.toString();
+    }
+
+    // 生成初中题：至少包含一个 ^2 或 sqrt()
+    private String genMiddle(int operands) {
+      // 基本表达式生成，后插入平方或开根号
+      String expr = genPrimary(operands); // 基本算术
+      // 2选1
+      if (RAND.nextBoolean()) {
+        // 找一个数字位置并替换为 (x)^2
+        expr = applySquare(expr);
+      } else {
+        expr = applySqrt(expr);
+      }
+      return expr;
+    }
+
+    // 生成高中题：至少包含 sin/cos/tan
+    private String genHigh(int operands) {
+      String expr = genPrimary(operands);
+      expr = applyTrig(expr);
+      return expr;
+    }
+
+    // 把表达式中某个数字替换为 (x)^2
+    private String applySquare(String expr) {
+      // 寻找所有数字的片段
+      List<int[]> spans = findNumberSpans(expr);
+      if (spans.isEmpty()) {
+        return expr + "^2";
+      }
+      int[] s = spans.get(RAND.nextInt(spans.size()));
+      String before = expr.substring(0, s[0]);
+      String num = expr.substring(s[0], s[1]);
+      String after = expr.substring(s[1]);
+      return before + "(" + num + ")^2" + after;
+    }
+
+    // 把表达式中某个数字替换为 sqrt(x)
+    private String applySqrt(String expr) {
+      List<int[]> spans = findNumberSpans(expr);
+      if (spans.isEmpty()) {
+        return "sqrt(" + expr + ")";
+      }
+      int[] s = spans.get(RAND.nextInt(spans.size()));
+      String before = expr.substring(0, s[0]);
+      String num = expr.substring(s[0], s[1]);
+      String after = expr.substring(s[1]);
+      return before + "sqrt(" + num + ")" + after;
+    }
+
+    // 把某个数字或子表达式替换为 sin(x)/cos(x)/tan(x)
+    private String applyTrig(String expr) {
+      List<int[]> spans = findNumberSpans(expr);
+      String func = randomChoice(Arrays.asList("sin", "cos", "tan"));
+      if (spans.isEmpty()) {
+        return func + "(" + expr + ")";
+      }
+      int[] s = spans.get(RAND.nextInt(spans.size()));
+      String before = expr.substring(0, s[0]);
+      String num = expr.substring(s[0], s[1]);
+      String after = expr.substring(s[1]);
+      return before + func + "(" + num + ")" + after;
+    }
+
+    // 找出数字位置
+    private List<int[]> findNumberSpans(String expr) {
+      List<int[]> spans = new ArrayList<>();
+      char[] chs = expr.toCharArray();
+      int i = 0, n = chs.length;
+      while (i < n) {
+        if (Character.isDigit(chs[i])) {
+          int j = i;
+          while (j < n && (Character.isDigit(chs[j]))) {
+            j++;
+          }
+          spans.add(new int[]{i, j});
+          i = j;
+        } else {
+          i++;
         }
+      }
+      return spans;
+    }
+
+    //a..b随机数
+    private int randInt(int a, int b) {
+      return RAND.nextInt(b - a + 1) + a;
+    }
+
+    //抽签功能
+    private <T> T randomChoice(List<T> list) {
+      return list.get(RAND.nextInt(list.size()));
     }
+  }
 }
diff --git a/src/Main.java b/src/Main.java
index 3fdfa19..3071822 100644
--- a/src/Main.java
+++ b/src/Main.java
@@ -1,67 +1,77 @@
 import java.nio.charset.StandardCharsets;
-import java.util.*;
+import java.util.List;
+import java.util.Scanner;
 
 public class Main {
-    private static final Scanner scanner = new Scanner(System.in, StandardCharsets.UTF_8);
-    public static void main(String[] args) {
-        System.out.println("=== 中小学数学卷子自动生成程序 ===");
-        while (true) {
-            Login.Account user = Login.LoginLoop();
-            if (user == null) continue;
-            Login.Level currentLevel = user.level;
-            System.out.println("当前选择为 " + LanguageSwitch.levelToChinese(currentLevel) + "出题");
-            boolean loggedIn = true;
-            while (loggedIn) {
-                System.out.print("系统提示“准备生成 " + LanguageSwitch.levelToChinese(currentLevel) + "数学题目，请输入生成题目数量（输入-1将退出当前用户，重新登录）：”\n> ");
-                String line = scanner.nextLine().trim();
-                if (line.equals("-1")) {
-                    System.out.println("退出当前用户，返回登录界面。");
-                    loggedIn = false;
-                    break;
-                }
-                if (line.startsWith("切换为")) {
-                    String target = line.substring("切换为".length()).trim();
-                    if (target.isEmpty()) {
-                        System.out.println("请输入小学、初中和高中三个选项中的一个");
-                        continue;
-                    }
-                    Login.Level newLevel = LanguageSwitch.chineseToLevel(target);
-                    if (newLevel == null) {
-                        System.out.println("请输入小学、初中和高中三个选项中的一个");
-                    } else {
-                        currentLevel = newLevel;
-                        System.out.println("切换成功。当前选择为 " + LanguageSwitch.levelToChinese(currentLevel) + "出题");
-                    }
-                    continue;
-                }
-                int n;
-                try {
-                    n = Integer.parseInt(line);
-                } catch (NumberFormatException e) {
-                    System.out.println("请输入有效的整数（10-30，或-1退出）或 '切换为 XX'。");
-                    continue;
-                }
-                if (n == -1) {
-                    System.out.println("退出当前用户，返回登录界面。");
-                    loggedIn = false;
-                    break;
-                }
-                if (n < 10 || n > 30) {
-                    System.out.println("题目数量的有效输入范围是“10-30”（含10,30，或-1退出登录）。");
-                    continue;
-                }
-                // 生成题目
-                List<String> existing = LoadFile.loadExistingQuestions(user.username);
-                Generator.QuestionGenerator qg = new Generator.QuestionGenerator(currentLevel, existing);
-                List<String> paper = qg.generatePaper(n);
-                if (paper.isEmpty()) {
-                    System.out.println("未能生成题目（可能因去重约束导致）。");
-                } else {
-                    // 保存文件
-                    String savedPath = Save.savePaper(user.username, paper);
-                    System.out.println("已生成 " + paper.size() + " 道题，保存为: " + savedPath);
-                }
-            }
+
+  /**
+   * 主程序：中小学数学卷子自动生成器。
+   */
+  private static final Scanner SCANNER = new Scanner(System.in, StandardCharsets.UTF_8);
+
+  public static void main(String[] args) {
+    System.out.println("=== 中小学数学卷子自动生成程序 ===");
+    while (true) {
+      Login.Account user = Login.loginLoop();
+      if (user == null) {
+        continue;
+      }
+      Login.Level currentLevel = user.level;
+      System.out.println("当前选择为 " + LanguageSwitch.levelToChinese(currentLevel) + "出题");
+      boolean loggedIn = true;
+      while (loggedIn) {
+        System.out.print("系统提示“准备生成 " + LanguageSwitch.levelToChinese(currentLevel)
+            + "数学题目，请输入生成题目数量（输入-1将退出当前用户，重新登录）：”\n> ");
+        String line = SCANNER.nextLine().trim();
+        if (line.equals("-1")) {
+          System.out.println("退出当前用户，返回登录界面。");
+          loggedIn = false;
+          break;
+        }
+        if (line.startsWith("切换为")) {
+          String target = line.substring("切换为".length()).trim();
+          if (target.isEmpty()) {
+            System.out.println("请输入小学、初中和高中三个选项中的一个");
+            continue;
+          }
+          Login.Level newLevel = LanguageSwitch.chineseToLevel(target);
+          if (newLevel == null) {
+            System.out.println("请输入小学、初中和高中三个选项中的一个");
+          } else {
+            currentLevel = newLevel;
+            System.out.println(
+                "切换成功。当前选择为 " + LanguageSwitch.levelToChinese(currentLevel) + "出题");
+          }
+          continue;
+        }
+        int n;
+        try {
+          n = Integer.parseInt(line);
+        } catch (NumberFormatException e) {
+          System.out.println("请输入有效的整数（10-30，或-1退出）或 '切换为 XX'。");
+          continue;
+        }
+        if (n == -1) {
+          System.out.println("退出当前用户，返回登录界面。");
+          loggedIn = false;
+          break;
+        }
+        if (n < 10 || n > 30) {
+          System.out.println("题目数量的有效输入范围是“10-30”（含10,30，或-1退出登录）。");
+          continue;
+        }
+        // 生成题目
+        List<String> existing = LoadFile.loadExistingQuestions(user.username);
+        Generator.QuestionGenerator qg = new Generator.QuestionGenerator(currentLevel, existing);
+        List<String> paper = qg.generatePaper(n);
+        if (paper.isEmpty()) {
+          System.out.println("未能生成题目（可能因去重约束导致）。");
+        } else {
+          // 保存文件
+          String savedPath = Save.savePaper(user.username, paper);
+          System.out.println("已生成 " + paper.size() + " 道题，保存为: " + savedPath);
         }
+      }
     }
+  }
 }
\ No newline at end of file
diff --git a/src/Save.java b/src/Save.java
index d1d4c25..bc100a9 100644
--- a/src/Save.java
+++ b/src/Save.java
@@ -1,34 +1,53 @@
-import java.io.*;
-import java.nio.file.*;
-import java.util.*;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.Files;
+import java.util.List;
+import java.util.Date;
 import java.text.SimpleDateFormat;
 import java.nio.charset.StandardCharsets;
+
+/**
+ * 工具类：负责保存生成的试卷到用户目录。
+ */
+
 public class Save {
-    // 保存试卷，返回保存路径字符串
-    public static String savePaper(String username, List<String> paper) {
-        Path userDir = Paths.get("data", username);
-        //识别文件夹
-        try {
-            if (!Files.exists(userDir)) Files.createDirectories(userDir);
-        } catch (IOException e) {
-            System.out.println("无法创建用户文件夹：" + e.getMessage());
-            return "保存失败";
-        }
-        String timestamp = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss").format(new Date());
-        Path file = userDir.resolve(timestamp + ".txt");
-        try (BufferedWriter bw = Files.newBufferedWriter(file, StandardCharsets.UTF_8)) {
-            for (int i = 0; i < paper.size(); i++) {
-                bw.write((i+1) + ". " + paper.get(i));
-                //换行
-                bw.newLine();
-                //空一行
-                bw.newLine();
-            }
-        } catch (IOException e) {
-            System.out.println("保存文件失败：" + e.getMessage());
-            return "保存失败";
-        }
-        //返回文件位置
-        return file.toString();
+
+  /**
+   * 保存试卷，并返回保存的文件路径。
+   *
+   * @param username 用户名
+   * @param paper    试卷内容
+   * @return 保存文件的路径字符串，若失败返回 "保存失败"
+   */
+  // 保存试卷，返回保存路径字符串
+  public static String savePaper(String username, List<String> paper) {
+    Path userDir = Paths.get("data", username);
+    //识别文件夹
+    try {
+      if (!Files.exists(userDir)) {
+        Files.createDirectories(userDir);
+      }
+    } catch (IOException e) {
+      System.err.println("无法创建用户文件夹：" + e.getMessage());
+      return "保存失败";
     }
+    String timestamp = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss").format(new Date());
+    Path file = userDir.resolve(timestamp + ".txt");
+    try (BufferedWriter bw = Files.newBufferedWriter(file, StandardCharsets.UTF_8)) {
+      for (int i = 0; i < paper.size(); i++) {
+        bw.write((i + 1) + ". " + paper.get(i));
+        //换行
+        bw.newLine();
+        //空一行
+        bw.newLine();
+      }
+    } catch (IOException e) {
+      System.err.println("保存文件失败：" + e.getMessage());
+      return "保存失败";
+    }
+    //返回文件位置
+    return file.toString();
+  }
 }
diff --git a/src/languageSwitch.java b/src/languageSwitch.java
index fcd84be..d793c4d 100644
--- a/src/languageSwitch.java
+++ b/src/languageSwitch.java
@@ -1,21 +1,23 @@
 public class LanguageSwitch {
-    //等级转中文输出
-    public static String levelToChinese(Login.Level l) {
-        return switch (l) {
-            case PRIMARY -> "小学";
-            case MIDDLE -> "初中";
-            case HIGH -> "高中";
-            //default -> "未知";
-        };
-    }
-    //等级中文输入转level
-    public static Login.Level chineseToLevel(String s) {
-        s = s.trim();//去除前后空格
-        return switch (s) {
-            case "小学" -> Login.Level.PRIMARY;
-            case "初中" -> Login.Level.MIDDLE;
-            case "高中" -> Login.Level.HIGH;
-            default -> null;
-        };
-    }
+
+  //等级转中文输出
+  public static String levelToChinese(Login.Level l) {
+    return switch (l) {
+      case PRIMARY -> "小学";
+      case MIDDLE -> "初中";
+      case HIGH -> "高中";
+      //default -> "未知";
+    };
+  }
+
+  //等级中文输入转level
+  public static Login.Level chineseToLevel(String s) {
+    s = s.trim();//去除前后空格
+    return switch (s) {
+      case "小学" -> Login.Level.PRIMARY;
+      case "初中" -> Login.Level.MIDDLE;
+      case "高中" -> Login.Level.HIGH;
+      default -> null;
+    };
+  }
 }
diff --git a/src/loadFile.java b/src/loadFile.java
index 600245e..7e44bb3 100644
--- a/src/loadFile.java
+++ b/src/loadFile.java
@@ -1,49 +1,68 @@
 import java.nio.charset.StandardCharsets;
-import java.io.*;
-import java.nio.file.*;
-import java.util.*;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.Files;
+import java.nio.file.DirectoryStream;
+import java.util.List;
+import java.util.ArrayList;
 import java.util.stream.Collectors;
+
 public class LoadFile {
-    // 读取该用户文件夹下已有题目的所有题目文本
-    public static List<String> loadExistingQuestions(String username) {
-        List<String> all = new ArrayList<>();
-        Path userDir = Paths.get("data", username);
-        if (!Files.exists(userDir)) return all;
-        try {
-            DirectoryStream<Path> ds = Files.newDirectoryStream(userDir, "*.txt");
-            for (Path p : ds) {
-                List<String> lines = Files.readAllLines(p, StandardCharsets.UTF_8);
-                // 将文件中按题号拆分题目
-                StringBuilder cur = new StringBuilder();
-                for (String line : lines) {
-                    //识别题号
-                    if (line.matches("^\\s*\\d+\\..*")) {
-                        // 新题开始 保存旧题
-                        if (!cur.isEmpty()) {
-                            all.add(cur.toString().trim());
-                        }
-                        cur.setLength(0);
-                        //去题号
-                        cur.append(line.replaceFirst("^\\s*\\d+\\.", "").trim());
-                    } else {
-                        // 继续当前题（空行也可能出现）
-                        if (line.trim().isEmpty()) {
-                            if (!cur.isEmpty()) {
-                                all.add(cur.toString().trim());
-                                cur.setLength(0);
-                            }
-                        } else {
-                            if (!cur.isEmpty()) cur.append(" ");
-                            cur.append(line.trim());
-                        }
-                    }
-                }
-                if (!cur.isEmpty()) all.add(cur.toString().trim());
+
+  /**
+   * 读取该用户文件夹下已有题目的所有题目文本。
+   *
+   * @param username 用户名
+   * @return 已存在的所有题目列表
+   */
+  // 读取该用户文件夹下已有题目的所有题目文本
+  public static List<String> loadExistingQuestions(String username) {
+    List<String> all = new ArrayList<>();
+    Path userDir = Paths.get("data", username);
+    if (!Files.exists(userDir)) {
+      return all;
+    }
+    try {
+      DirectoryStream<Path> ds = Files.newDirectoryStream(userDir, "*.txt");
+      for (Path p : ds) {
+        List<String> lines = Files.readAllLines(p, StandardCharsets.UTF_8);
+        // 将文件中按题号拆分题目
+        StringBuilder cur = new StringBuilder();
+        for (String line : lines) {
+          //识别题号
+          if (line.matches("^\\s*\\d+\\..*")) {
+            // 新题开始 保存旧题
+            if (!cur.isEmpty()) {
+              all.add(cur.toString().trim());
             }
-        } catch (IOException e) {
-            // ignore, return what we have
+            cur.setLength(0);
+            //去题号
+            cur.append(line.replaceFirst("^\\s*\\d+\\.", "").trim());
+          } else {
+            // 继续当前题（空行也可能出现）
+            if (line.trim().isEmpty()) {
+              if (!cur.isEmpty()) {
+                all.add(cur.toString().trim());
+                cur.setLength(0);
+              }
+            } else {
+              if (!cur.isEmpty()) {
+                cur.append(" ");
+              }
+              cur.append(line.trim());
+            }
+          }
+        }
+        if (!cur.isEmpty()) {
+          all.add(cur.toString().trim());
         }
-        // 转链式 去空格 去空字符串 去重 转回list
-        return all.stream().map(String::trim).filter(s->!s.isEmpty()).distinct().collect(Collectors.toList());
-   }
+      }
+    } catch (IOException e) {
+      System.err.println("读取题目文件失败：" + e.getMessage());
+    }
+    // 转链式 去空格 去空字符串 去重 转回list
+    return all.stream().map(String::trim).filter(s -> !s.isEmpty()).distinct()
+        .collect(Collectors.toList());
+  }
 }
diff --git a/src/login.java b/src/login.java
index e58b18f..78a20b4 100644
--- a/src/login.java
+++ b/src/login.java
@@ -4,56 +4,62 @@ import java.util.Map;
 import java.util.Scanner;
 
 public class Login {
-    public static class Account {
-        String username;//用户名
-        String password;//密码
-        Level level;//出题等级
-        Account(String u, String p, Level l) {
-            username = u;
-            password = p;
-            level = l;
-        }
-    }
-    enum Level { PRIMARY, MIDDLE, HIGH }
-
-    private static final Map<String, Account> accounts = new HashMap<>();
-    private static final Scanner scanner = new Scanner(System.in, StandardCharsets.UTF_8);
-
-    // 初始化预设账号
-    // 初始Map索引
-    static {
-        // 小学 张三1..3
-        accounts.put("张三1", new Account("张三1","123", Level.PRIMARY));
-        accounts.put("张三2", new Account("张三2","123", Level.PRIMARY));
-        accounts.put("张三3", new Account("张三3","123", Level.PRIMARY));
-        // 初中 李四1..3
-        accounts.put("李四1", new Account("李四1","123", Level.MIDDLE));
-        accounts.put("李四2", new Account("李四2","123", Level.MIDDLE));
-        accounts.put("李四3", new Account("李四3","123", Level.MIDDLE));
-        // 高中 王五1..3
-        accounts.put("王五1", new Account("王五1","123", Level.HIGH));
-        accounts.put("王五2", new Account("王五2","123", Level.HIGH));
-        accounts.put("王五3", new Account("王五3","123", Level.HIGH));
+
+  public static class Account {
+
+    String username;//用户名
+    String password;//密码
+    Level level;//出题等级
+
+    Account(String u, String p, Level l) {
+      username = u;
+      password = p;
+      level = l;
     }
-    public static Account LoginLoop() {
-        while (true) {
-            System.out.print("请输入用户名和密码，两者之间用空格隔开：\n> ");
-            String line = scanner.nextLine().trim();//行输入；
-            String[] parts = line.split("\\s+");//拆分输入的账号密码，拆分标志为空格；
-            //正常情况下parts.length=2;
-            if (parts.length != 2) {
-                System.out.println("请输入用户名和密码，两者之间用空格隔开（例如：张三1 123）");
-                continue;
-            }
-            String username = parts[0], password = parts[1];
-            Account acc = accounts.get(username);
-
-            if (acc != null && acc.password.equals(password)) {
-                System.out.println("登录成功。当前选择为 " + LanguageSwitch.levelToChinese(acc.level) + "出题");
-                return acc;
-            } else {
-                System.out.println("请输入正确的用户名、密码");
-            }
-        }
+  }
+
+  enum Level {PRIMARY, MIDDLE, HIGH}
+
+  private static final Map<String, Account> accounts = new HashMap<>();
+  private static final Scanner scanner = new Scanner(System.in, StandardCharsets.UTF_8);
+
+  // 初始化预设账号
+  // 初始Map索引
+  static {
+    // 小学 张三1..3
+    accounts.put("张三1", new Account("张三1", "123", Level.PRIMARY));
+    accounts.put("张三2", new Account("张三2", "123", Level.PRIMARY));
+    accounts.put("张三3", new Account("张三3", "123", Level.PRIMARY));
+    // 初中 李四1..3
+    accounts.put("李四1", new Account("李四1", "123", Level.MIDDLE));
+    accounts.put("李四2", new Account("李四2", "123", Level.MIDDLE));
+    accounts.put("李四3", new Account("李四3", "123", Level.MIDDLE));
+    // 高中 王五1..3
+    accounts.put("王五1", new Account("王五1", "123", Level.HIGH));
+    accounts.put("王五2", new Account("王五2", "123", Level.HIGH));
+    accounts.put("王五3", new Account("王五3", "123", Level.HIGH));
+  }
+
+  public static Account loginLoop() {
+    while (true) {
+      System.out.print("请输入用户名和密码，两者之间用空格隔开：\n> ");
+      String line = scanner.nextLine().trim();//行输入；
+      String[] parts = line.split("\\s+");//拆分输入的账号密码，拆分标志为空格；
+      //正常情况下parts.length=2;
+      if (parts.length != 2) {
+        System.out.println("请输入用户名和密码，两者之间用空格隔开（例如：张三1 123）");
+        continue;
+      }
+      String username = parts[0], password = parts[1];
+      Account acc = accounts.get(username);
+
+      if (acc != null && acc.password.equals(password)) {
+        System.out.println(
+            "登录成功。当前选择为 " + LanguageSwitch.levelToChinese(acc.level) + "出题");
+        return acc;
+      } else {
+        System.out.println("请输入正确的用户名、密码");
+      }
     }
+  }
 }