优化

src/languageSwitch.java

@@ -5,7 +5,7 @@ public class languageSwitch {
             case PRIMARY -> "小学";
             case MIDDLE -> "初中";
             case HIGH -> "高中";
-            default -> "未知";
+            //default -> "未知";
         };
     }
     //等级中文输入转level

src/loadFile.java

@@ -4,7 +4,7 @@ import java.nio.file.*;
 import java.util.*;
 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（每行一个题目或跨行拼接）
+    // 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);
@@ -13,37 +13,37 @@ public class loadFile {
             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 —— 假设格式 "1. xxx" 开头。我们做简单处理：每个题号开头的新题。
+                // 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.length() > 0) {
+                        // 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()) {
-                            // treat as separator; finish current if non-empty
-                            if (cur.length() > 0) {
+                            if (!cur.isEmpty()) {
                                 all.add(cur.toString().trim());
                                 cur.setLength(0);
                             }
                         } else {
-                            if (cur.length() > 0) cur.append(" ");
+                            if (!cur.isEmpty()) cur.append(" ");
                             cur.append(line.trim());
                         }
                     }
                 }
-                if (cur.length() > 0) all.add(cur.toString().trim());
+                if (!cur.isEmpty()) all.add(cur.toString().trim());
             }
         } catch (IOException e) {
             // ignore, return what we have
         }
-        // dedupe and return
+        // 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());
-    }
-
+   }
 }

src/login.java

@@ -1,7 +1,6 @@
 import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Random;
 import java.util.Scanner;
 
 public class login {
@@ -19,7 +18,6 @@ public class login {
 
     private static final Map<String, Account> accounts = new HashMap<>();
     private static final Scanner scanner = new Scanner(System.in, StandardCharsets.UTF_8);
-    //private static final Random rand = new Random();
 
     // 初始化预设账号
     // 初始Map索引

src/questionGenerator.java

@@ -5,10 +5,10 @@ import java.util.stream.Collectors;
 
 public class questionGenerator {
     private static final Random rand = new Random();
+
     static class QuestionGenerator {
         private final login.Level level;
         private final Set<String> existing;
-        private final int maxAttempts = 2000; // 防止死循环
 
         QuestionGenerator(login.Level level, List<String> existingQuestions) {
             this.level = level;
@@ -18,6 +18,8 @@ public class questionGenerator {
         List<String> generatePaper(int n) {
             Set<String> generated = new LinkedHashSet<>();
             int attempts = 0;
+            // 防止死循环
+            int maxAttempts = 2000;
             while (generated.size() < n && attempts < maxAttempts) {
                 attempts++;
                 String q = generateOneQuestion();
@@ -37,16 +39,14 @@ public class questionGenerator {
             return s.replaceAll("\\s+","").toLowerCase();
         }
 
-        // 生成单题主逻辑
         // 生成单题主逻辑
         private String generateOneQuestion() {
             int operands = rand.nextInt(4) + 2; // 保证 2..5 个操作数
-            switch (level) {
-                case PRIMARY: return genPrimary(operands);
-                case MIDDLE: return genMiddle(operands);
-                case HIGH: return genHigh(operands);
-                default: return genPrimary(operands);
-            }
+            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) {

src/savepaper.java

@@ -7,6 +7,7 @@ public class savepaper {
     // 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) {
@@ -18,14 +19,16 @@ public class savepaper {
         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();
     }
-
 }