// 舊方式
List<String> list = Collections.unmodifiableList(Arrays.asList("Java", "Kotlin", "Scala"));
Map<String, Integer> map = Collections.unmodifiableMap(new HashMap<String, Integer>() {{
    put("Java", 1995);
    put("Kotlin", 2011);
    put("Scala", 2004);
}});

// JDK9方式
List<String> list = List.of("Java", "Kotlin", "Scala");
Set<String> set = Set.of("Java", "Kotlin", "Scala");
Map<String, Integer> map = Map.of(
    "Java", 1995,
    "Kotlin", 2011,
    "Scala", 2004
);

Map<String, Integer> largeMap = Map.ofEntries(
    Map.entry("Java", 1995),
    Map.entry("Kotlin", 2011),
    Map.entry("Scala", 2004),
    Map.entry("Groovy", 2003)
    // ...可以有更多entries
);

public interface FileProcessor {
    // 公共抽象方法
    void process(Path path);
    
    // 默認(rèn)方法
    default void processFile(String fileName) {
        validateFileName(fileName); // 復(fù)用私有方法進(jìn)行驗(yàn)證
        process(Path.of(fileName));
        log("Processed file: " + fileName);
    }
    
    default void processDirectory(String dirName) {
        validateFileName(dirName); // 復(fù)用相同的驗(yàn)證邏輯
        try (Stream<Path> paths = Files.list(Path.of(dirName))) {
            paths.forEach(this::process);
        } catch (IOException e) {
            handleException(e); // 復(fù)用私有方法處理異常
        }
        log("Processed directory: " + dirName);
    }
    
    // 私有方法 - 供默認(rèn)方法使用
    private void validateFileName(String fileName) {
        if (fileName == null || fileName.isEmpty()) {
            throw new IllegalArgumentException("File name cannot be empty");
        }
    }
    
    // 私有靜態(tài)方法
    private static void log(String message) {
        System.out.println("[" + LocalDateTime.now() + "] " + message);
    }
    
    private void handleException(Exception e) {
        log("Error: " + e.getMessage());
    }
}

// 1. takeWhile - 從頭開(kāi)始獲取元素，直到條件不滿足
Stream.of(2, 4, 6, 8, 9, 10, 12)
      .takeWhile(n -> n % 2 == 0) // 結(jié)果: [2, 4, 6, 8]
      .forEach(System.out::println);

// 2. dropWhile - 從頭開(kāi)始丟棄元素，直到條件不滿足
Stream.of(2, 4, 6, 8, 9, 10, 12)
      .dropWhile(n -> n % 2 == 0) // 結(jié)果: [9, 10, 12]
      .forEach(System.out::println);

// 3. ofNullable - 安全創(chuàng)建單元素流，處理null值
Stream.ofNullable(null).count(); // 0
Stream.ofNullable("Java").count(); // 1

// 4. iterate方法重載 - 帶終止條件的迭代
// 舊方式需要使用limit或filter來(lái)限制
Stream.iterate(1, n -> n * 2)
      .limit(5)
      .forEach(System.out::println);

// 新方式更直接
Stream.iterate(1, n -> n < 100, n -> n * 2)
      .forEach(System.out::println); // 1, 2, 4, 8, 16, 32, 64

// 舊方式 - 冗長(zhǎng)且易錯(cuò)
try (InputStream is = new FileInputStream("source.txt");
     OutputStream os = new FileOutputStream("target.txt")) {
    byte[] buffer = new byte[8192];
    int length;
    while ((length = is.read(buffer)) > 0) {
        os.write(buffer, 0, length);
    }
}

// JDK9方式 - 簡(jiǎn)潔明了
try (InputStream is = new FileInputStream("source.txt");
     OutputStream os = new FileOutputStream("target.txt")) {
    is.transferTo(os); // 一行代碼搞定
}

// 獲取當(dāng)前進(jìn)程
ProcessHandle current = ProcessHandle.current();
System.out.println("Current PID: " + current.pid());

// 獲取進(jìn)程信息
current.info().user().ifPresent(user -> System.out.println("User: " + user));
current.info().commandLine().ifPresent(cmd -> System.out.println("Command: " + cmd));
current.info().startInstant().ifPresent(start -> System.out.println("Start time: " + start));
current.info().totalCpuDuration().ifPresent(cpu -> System.out.println("CPU time: " + cpu));

// 列出所有子進(jìn)程
current.children().forEach(child -> System.out.println("Child PID: " + child.pid()));

// 列出所有進(jìn)程
ProcessHandle.allProcesses()
    .filter(ph -> ph.info().command().isPresent())
    .forEach(ph -> System.out.println(ph.pid() + ": " + ph.info().command().get()));

// 啟動(dòng)并等待進(jìn)程完成
ProcessBuilder pb = new ProcessBuilder("ls", "-l");
Process process = pb.start();
ProcessHandle handle = process.toHandle();
boolean terminated = handle.onExit().thenAccept(p -> 
    System.out.println("Process " + p.pid() + " terminated")
).isDone();

// 舊方式 - 類型重復(fù)且冗長(zhǎng)
HashMap<String, List<Customer>> customersByCity = new HashMap<>();
BufferedReader reader = new BufferedReader(new FileReader("data.txt"));
URLConnection connection = new URL("https://example.com").openConnection();

// JDK10方式 - 簡(jiǎn)潔明了
var customersByCity = new HashMap<String, List<Customer>>();
var reader = new BufferedReader(new FileReader("data.txt"));
var connection = new URL("https://example.com").openConnection();

// 在for循環(huán)中特別有用
for (var entry : customersByCity.entrySet()) {
    var city = entry.getKey();
    var customers = entry.getValue();
    // ...
}

// 好的用法 - 類型明確
var customers = new ArrayList<Customer>();
var entry = Map.entry("key", "value");

// 避免的用法 - 類型不明確
var result = getResult(); // 返回類型不明顯
var x = 1; // 基本類型推薦顯式聲明

// 原始集合
List<String> original = new ArrayList<>(List.of("Java", "Kotlin", "Scala"));
Set<Integer> originalSet = new HashSet<>(Set.of(1, 2, 3));
Map<String, Integer> originalMap = new HashMap<>(Map.of("one", 1, "two", 2));

// 創(chuàng)建不可修改的副本
List<String> copy = List.copyOf(original);
Set<Integer> copiedSet = Set.copyOf(originalSet);
Map<String, Integer> copiedMap = Map.copyOf(originalMap);

// 修改原集合不影響副本
original.add("Groovy");
System.out.println(original); // [Java, Kotlin, Scala, Groovy]
System.out.println(copy);     // [Java, Kotlin, Scala]

// 嘗試修改副本會(huì)拋出異常
try {
    copy.add("Clojure"); // 拋出 UnsupportedOperationException
} catch (UnsupportedOperationException e) {
    System.out.println("Cannot modify immutable copy");
}

// 1. lines() - 按行分割字符串
String multiline = "Java\nKotlin\nScala";
multiline.lines()
    .map(String::toUpperCase)
    .forEach(System.out::println);

// 2. strip(), stripLeading(), stripTrailing() - 去除空白字符
String text = "  Hello World  ";
System.out.println(">" + text.strip() + "<");          // >Hello World<
System.out.println(">" + text.stripLeading() + "<");   // >Hello World  <
System.out.println(">" + text.stripTrailing() + "<");  // >  Hello World<

// strip()與trim()的區(qū)別: strip()識(shí)別更多的Unicode空白字符
String unicodeWhitespace = "\u2005Hello\u2005";
System.out.println(">" + unicodeWhitespace.trim() + "<");   // >?Hello?<
System.out.println(">" + unicodeWhitespace.strip() + "<");  // >Hello<

// 3. isBlank() - 檢查字符串是否為空白
System.out.println("  ".isBlank());     // true
System.out.println("".isBlank());       // true
System.out.println(" a ".isBlank());    // false

// 4. repeat() - 重復(fù)字符串
String star = "*";
System.out.println(star.repeat(10));    // **********
System.out.println("=".repeat(20));     // ====================

// 讀取文件為String
String content = Files.readString(Path.of("config.json"));

// 寫(xiě)入String到文件
Files.writeString(Path.of("output.txt"), "Hello Java 11!");

// 使用指定編碼
String content = Files.readString(Path.of("data.txt"), StandardCharsets.UTF_8);
Files.writeString(Path.of("log.txt"), "Logged at: " + LocalDateTime.now(), 
                 StandardCharsets.UTF_8);

// 寫(xiě)入字符串集合
List<String> lines = List.of("Line 1", "Line 2", "Line 3");
Files.write(Path.of("lines.txt"), lines);

// 創(chuàng)建HTTP客戶端
HttpClient client = HttpClient.newBuilder()
    .connectTimeout(Duration.ofSeconds(10))
    .build();

// 構(gòu)建GET請(qǐng)求
HttpRequest request = HttpRequest.newBuilder()
    .uri(URI.create("https://api.github.com/users/octocat"))
    .header("User-Agent", "Java 11 HttpClient")
    .GET()
    .build();

// 同步發(fā)送請(qǐng)求，接收J(rèn)SON響應(yīng)
HttpResponse<String> response = client.send(request, 
    HttpResponse.BodyHandlers.ofString());

System.out.println("Status code: " + response.statusCode());
System.out.println("Body: " + response.body());

// POST請(qǐng)求示例
HttpRequest postRequest = HttpRequest.newBuilder()
    .uri(URI.create("https://httpbin.org/post"))
    .header("Content-Type", "application/json")
    .POST(HttpRequest.BodyPublishers.ofString("{"name": "Java"}"))
    .build();

// 異步發(fā)送請(qǐng)求
client.sendAsync(postRequest, HttpResponse.BodyHandlers.ofString())
    .thenApply(HttpResponse::body)
    .thenAccept(System.out::println)
    .join();

// 處理JSON響應(yīng)(需要JSON庫(kù))
client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
    .thenApply(HttpResponse::body)
    .thenApply(body -> {
        // 使用Jackson或Gson解析JSON
        return body;
    })
    .thenAccept(System.out::println)
    .join();

// 創(chuàng)建簡(jiǎn)短格式的格式化器
NumberFormat shortFormatter = NumberFormat.getCompactNumberInstance(
    Locale.US, NumberFormat.Style.SHORT);

// 格式化數(shù)字
System.out.println(shortFormatter.format(1000));       // 1K
System.out.println(shortFormatter.format(1500));       // 2K (四舍五入)
System.out.println(shortFormatter.format(1000000));    // 1M
System.out.println(shortFormatter.format(1000000000)); // 1B

// 長(zhǎng)格式
NumberFormat longFormatter = NumberFormat.getCompactNumberInstance(
    Locale.US, NumberFormat.Style.LONG);
System.out.println(longFormatter.format(1000));        // 1 thousand
System.out.println(longFormatter.format(1000000));     // 1 million

// 其他語(yǔ)言的格式化
NumberFormat germanFormatter = NumberFormat.getCompactNumberInstance(
    Locale.GERMANY, NumberFormat.Style.SHORT);
System.out.println(germanFormatter.format(1000));      // 1.000

NumberFormat chineseFormatter = NumberFormat.getCompactNumberInstance(
    Locale.CHINA, NumberFormat.Style.SHORT);
System.out.println(chineseFormatter.format(1000));     // 1千
System.out.println(chineseFormatter.format(1000000));  // 100萬(wàn)

// 自定義精度
shortFormatter.setMaximumFractionDigits(1);
System.out.println(shortFormatter.format(1234));       // 1.2K
System.out.println(shortFormatter.format(1500));       // 1.5K

// 假設(shè)有這樣的代碼
User user = null;
String city = user.getAddress().getCity();

Exception in thread "main" java.lang.NullPointerException
    at Main.main(Main.java:5)

Exception in thread "main" java.lang.NullPointerException: 
  Cannot invoke "User.getAddress()" because "user" is null
    at Main.main(Main.java:5)

map.get("key").process().getNestedValue();

Exception in thread "main" java.lang.NullPointerException: 
  Cannot invoke "Result.getNestedValue()" because the return value of 
  "ProcessedData.process()" is null

// 傳統(tǒng)switch語(yǔ)句
String result;
DayOfWeek day = LocalDate.now().getDayOfWeek();

switch (day) {
    case MONDAY:
    case TUESDAY:
    case WEDNESDAY:
    case THURSDAY:
    case FRIDAY:
        result = "Weekday";
        break;
    case SATURDAY:
    case SUNDAY:
        result = "Weekend";
        break;
    default:
        result = "Invalid day";
        break;
}

// 新的switch表達(dá)式
String result = switch (day) {
    case MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY -> "Weekday";
    case SATURDAY, SUNDAY -> "Weekend";
    default -> "Invalid day";
};

// 復(fù)雜表達(dá)式，帶代碼塊
int numLetters = switch (day) {
    case MONDAY, FRIDAY, SUNDAY -> {
        System.out.println("Six letters day");
        yield 6;
    }
    case TUESDAY -> {
        System.out.println("Seven letters day");
        yield 7;
    }
    case THURSDAY, SATURDAY -> {
        System.out.println("Eight letters day");
        yield 8;
    }
    case WEDNESDAY -> {
        System.out.println("Nine letters day");
        yield 9;
    }
    default -> {
        throw new IllegalStateException("Invalid day: " + day);
    }
};

// 傳統(tǒng)POJO類
public final class Employee {
    private final String name;
    private final int id;
    private final Department department;
    
    public Employee(String name, int id, Department department) {
        this.name = name;
        this.id = id;
        this.department = department;
    }
    
    public String getName() { return name; }
    public int getId() { return id; }
    public Department getDepartment() { return department; }
    
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Employee employee = (Employee) o;
        return id == employee.id && 
               Objects.equals(name, employee.name) && 
               Objects.equals(department, employee.department);
    }
    
    @Override
    public int hashCode() {
        return Objects.hash(name, id, department);
    }
    
    @Override
    public String toString() {
        return "Employee{" +
               "name='" + name + ''' +
               ", id=" + id +
               ", department=" + department +
               '}';
    }
}

// 使用Record
public record Employee(String name, int id, Department department) { }

public record Point(int x, int y) {
    // 自定義緊湊構(gòu)造器
    public Point {
        if (x < 0 || y < 0) {
            throw new IllegalArgumentException("Coordinates cannot be negative");
        }
    }
    
    // 重載構(gòu)造器
    public Point() {
        this(0, 0);
    }
    
    // 實(shí)例方法
    public double distance(Point other) {
        return Math.sqrt(Math.pow(this.x - other.x, 2) + 
                          Math.pow(this.y - other.y, 2));
    }
    
    // 靜態(tài)成員
    public static final Point ORIGIN = new Point(0, 0);
    
    // 靜態(tài)方法
    public static Point of(int x, int y) {
        return new Point(x, y);
    }
}

// 傳統(tǒng)多行字符串
String json = "{\n" +
              "  "name": "John Doe",\n" +
              "  "age": 30,\n" +
              "  "address": {\n" +
              "    "street": "123 Main St",\n" +
              "    "city": "Anytown"\n" +
              "  }\n" +
              "}";

// 使用文本塊
String json = """
              {
                "name": "John Doe",
                "age": 30,
                "address": {
                  "street": "123 Main St",
                  "city": "Anytown"
                }
              }
              """;

// HTML示例
String html = """
              <html>
                <body>
                  <h1>Hello, World!</h1>
                </body>
              </html>
              """;

// SQL查詢
String query = """
               SELECT id, first_name, last_name
               FROM employees
               WHERE department_id = ?
               ORDER BY last_name, first_name
               """;

// 使用\避免行尾換行
String compact = """
                 <html>\
                 <body>\
                 <p>Hello</p>\
                 </body>\
                 </html>\
                 """;

// 與String::formatted配合使用
String template = """
                  Dear %s,
                  
                  Your order #%d has been shipped on %s.
                  
                  Thank you,
                  Customer Service
                  """;
                  
String message = template.formatted("John", 12345, "2023-05-15");

// 傳統(tǒng)方式
if (obj instanceof String) {
    String s = (String) obj;
    if (s.length() > 5) {
        System.out.println(s.toUpperCase());
    }
}

// 使用模式匹配
if (obj instanceof String s && s.length() > 5) {
    System.out.println(s.toUpperCase());
}

// 在復(fù)雜條件中使用
if (obj instanceof String s && s.length() > 10 
    || obj instanceof List<?> list && list.size() > 5) {
    // 使用s或list
}

// 與switch配合使用(JDK17預(yù)覽特性)
Object value = getValue();
switch (value) {
    case String s when s.length() > 5 -> System.out.println("Long string: " + s);
    case String s -> System.out.println("Short string: " + s);
    case List<?> l -> System.out.println("List with " + l.size() + " elements");
    default -> System.out.println("Unknown type");
}

// 分配堆外內(nèi)存
try (Arena arena = Arena.ofConfined()) {
    // 分配100字節(jié)的本地內(nèi)存
    MemorySegment segment = arena.allocate(100);
    
    // 寫(xiě)入數(shù)據(jù)
    MemorySegment.copy(new byte[] {1, 2, 3, 4, 5}, 0, segment, 0, 5);
    
    // 讀取數(shù)據(jù)
    byte value = segment.get(ValueLayout.JAVA_BYTE, 2); // 讀取索引2的值
    System.out.println("Value at index 2: " + value);   // 輸出 3
    
    // 填充內(nèi)存段
    MemorySegment.fill(segment, (byte) 10);
    
    // 使用VarHandle操作內(nèi)存
    VarHandle intHandle = ValueLayout.JAVA_INT.varHandle();
    intHandle.set(segment, 0, 42);
    int result = (int) intHandle.get(segment, 0);
    System.out.println("Integer value: " + result);     // 輸出 42
    
    // 內(nèi)存地址操作
    long address = segment.address().toRawLongValue();
    System.out.println("Memory address: 0x" + Long.toHexString(address));
}

// 聲明一個(gè)密封接口，只允許特定的類實(shí)現(xiàn)它
public sealed interface Shape 
    permits Circle, Rectangle, Triangle {
    double area();
}

// 最終實(shí)現(xiàn)類，不允許進(jìn)一步繼承
public final class Circle implements Shape {
    private final double radius;
    
    public Circle(double radius) {
        this.radius = radius;
    }
    
    @Override
    public double area() {
        return Math.PI * radius * radius;
    }
}

// 允許進(jìn)一步繼承的類
public non-sealed class Rectangle implements Shape {
    private final double width;
    private final double height;
    
    public Rectangle(double width, double height) {
        this.width = width;
        this.height = height;
    }
    
    @Override
    public double area() {
        return width * height;
    }
}

// 限制繼承的類
public sealed class Triangle implements Shape 
    permits EquilateralTriangle, RightTriangle {
    // ...實(shí)現(xiàn)...
}

// 允許的子類
public final class EquilateralTriangle extends Triangle {
    // ...實(shí)現(xiàn)...
}

public final class RightTriangle extends Triangle {
    // ...實(shí)現(xiàn)...
}

double calculateArea(Shape shape) {
    return switch (shape) {
        case Circle c -> Math.PI * c.radius() * c.radius();
        case Rectangle r -> r.width() * r.height();
        case Triangle t -> t.base() * t.height() / 2;
        // 不需要default分支，因?yàn)榫幾g器知道這些是Shape的所有可能實(shí)現(xiàn)
    };
}

// 獲取默認(rèn)的隨機(jī)數(shù)生成器
RandomGenerator random = RandomGenerator.getDefault();
System.out.println(random.nextInt(100)); // 0-99之間的隨機(jī)數(shù)

// 使用特定算法的生成器
RandomGenerator xoroshiro = RandomGenerator.of("Xoroshiro128PlusPlus");
System.out.println(xoroshiro.nextLong());

// 使用L32X64MixRandom - 平衡了速度和質(zhì)量的算法
RandomGenerator fastRandom = RandomGenerator.of("L32X64MixRandom");
for (int i = 0; i < 5; i++) {
    System.out.println(fastRandom.nextInt(1000));
}

// 創(chuàng)建可復(fù)現(xiàn)的隨機(jī)數(shù)序列 (使用相同的種子)
RandomGenerator seeded = RandomGenerator.of("Xoshiro256PlusPlus");
((SplittableRandomGenerator) seeded).setSeed(42);
for (int i = 0; i < 5; i++) {
    System.out.println(seeded.nextInt(100));
}

// 生成隨機(jī)流
DoubleStream randomDoubles = RandomGenerator.getDefault().doubles(1000);
randomDoubles.forEach(System.out::println);

// 查看所有可用的算法
RandomGenerator.all()
    .map(provider -> provider.name() + ": " + provider.group())
    .sorted()
    .forEach(System.out::println);

// 使用IntVector加速數(shù)組求和
static int sumArrayVectorized(int[] a) {
    var species = IntVector.SPECIES_PREFERRED;
    var sum = IntVector.zero(species);
    var i = 0;
    
    // 處理可以向量化的部分
    for (; i <= a.length - species.length(); i += species.length()) {
        var v = IntVector.fromArray(species, a, i);
        sum = sum.add(v);
    }
    
    // 處理剩余元素
    var result = sum.reduceLanes(VectorOperators.ADD);
    for (; i < a.length; i++) {
        result += a[i];
    }
    
    return result;
}

// 向量化矩陣乘法
static void multiplyMatricesVectorized(float[] a, float[] b, float[] c, int n) {
    var species = FloatVector.SPECIES_PREFERRED;
    int limit = species.length();
    
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            var sum = FloatVector.zero(species);
            int k = 0;
            
            // 使用向量計(jì)算
            for (; k <= n - limit; k += limit) {
                var va = FloatVector.fromArray(species, a, i * n + k);
                var vb = FloatVector.fromArray(species, b, k * n + j);
                sum = sum.add(va.mul(vb));
            }
            
            // 累加向量結(jié)果
            float dotProduct = sum.reduceLanes(VectorOperators.ADD);
            
            // 處理剩余元素
            for (; k < n; k++) {
                dotProduct += a[i * n + k] * b[k * n + j];
            }
            
            c[i * n + j] = dotProduct;
        }
    }
}

// 命令行用法
// jwebserver -p 8000 -d /path/to/directory

// 在代碼中使用:
import com.sun.net.httpserver.*;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.file.Path;

public class SimpleFileServer {
    public static void main(String[] args) throws IOException {
        var server = SimpleFileServer.createFileServer(
            new InetSocketAddress(8000), 
            Path.of("/path/to/directory"), 
            SimpleFileServer.OutputLevel.VERBOSE
        );
        server.start();
        System.out.println("Server started at http://localhost:8000");
    }
}

/**
 * This class provides utility methods for string operations.
 *
 * <p>Example usage:</p>
 * {@snippet :
 *   String result = StringUtils.capitalize("hello");  // Returns "Hello"
 *   boolean isEmpty = StringUtils.isBlank(" ");       // Returns true
 * }
 */
public class StringUtils {
    // 類實(shí)現(xiàn)省略
}

/**
 * Example of snippet with highlighting:
 * {@snippet :
 *   // @highlight region="important"
 *   String encoded = Base64.getEncoder().encodeToString(data);
 *   // @end
 *   
 *   // @highlight regex="data" type="bold"
 *   byte[] decoded = Base64.getDecoder().decode(encoded);
 *   
 *   // @replace regex="badPractice()" replacement="goodPractice()" type="error"
 *   result = badPractice();
 * }
 */

// 定義C庫(kù)函數(shù)的接口
import java.lang.foreign.*;
import static java.lang.foreign.ValueLayout.*;

public class LibCDemo {
    public static void main(String[] args) {
        // 獲取C標(biāo)準(zhǔn)庫(kù)的鏈接器
        Linker linker = Linker.nativeLinker();
        
        // 查找printf函數(shù)
        SymbolLookup stdlib = linker.defaultLookup();
        MethodHandle printf = stdlib.find("printf")
            .map(addr -> linker.downcallHandle(
                addr,
                FunctionDescriptor.of(JAVA_INT, ADDRESS),
                Linker.Option.firstVariadicArg(1)
            ))
            .orElseThrow();
        
        // 準(zhǔn)備字符串參數(shù)
        try (Arena arena = Arena.ofConfined()) {
            MemorySegment cString = arena.allocateUtf8String("Hello from Java! Count: %d\n");
            
            // 調(diào)用printf
            try {
                printf.invoke(cString, 42);
            } catch (Throwable e) {
                e.printStackTrace();
            }
        }
    }
}

// 創(chuàng)建和啟動(dòng)單個(gè)虛擬線程
Thread.startVirtualThread(() -> {
    System.out.println("Running in virtual thread");
});

// 使用虛擬線程運(yùn)行多個(gè)任務(wù)
try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
    // 提交1000個(gè)任務(wù)，每個(gè)在獨(dú)立的虛擬線程中運(yùn)行
    for (int i = 0; i < 1000; i++) {
        int taskId = i;
        executor.submit(() -> {
            System.out.println("Task " + taskId + " running on " + Thread.currentThread());
            // 模擬IO操作
            try {
                Thread.sleep(Duration.ofMillis(100));
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
            return taskId;
        });
    }
} // 自動(dòng)關(guān)閉executor

// 以構(gòu)建器方式創(chuàng)建虛擬線程
ThreadFactory factory = Thread.ofVirtual().name("worker-", 0).factory();
Thread worker = factory.newThread(() -> {
    // 任務(wù)代碼
});
worker.start();

// 使用虛擬線程改寫(xiě)傳統(tǒng)的阻塞式IO代碼
void processFile(Path file) throws IOException {
    // 這段代碼在虛擬線程中運(yùn)行時(shí)不會(huì)阻塞平臺(tái)線程
    try (var reader = Files.newBufferedReader(file)) {
        String line;
        while ((line = reader.readLine()) != null) {
            processLine(line);
        }
    }
}

// 并行獲取用戶及其訂單
record User(int id, String name) {}
record Order(int id, double amount) {}
record UserWithOrders(User user, List<Order> orders) {}

UserWithOrders getUserWithOrders(int userId) {
    try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
        // 并行執(zhí)行兩個(gè)子任務(wù)
        Future<User> userFuture = scope.fork(() -> fetchUser(userId));
        Future<List<Order>> ordersFuture = scope.fork(() -> fetchOrders(userId));
        
        // 等待所有任務(wù)完成
        scope.join();
        // 檢查子任務(wù)是否有異常
        scope.throwIfFailed(e -> new RuntimeException("Failed to fetch data", e));
        
        // 獲取結(jié)果
        return new UserWithOrders(userFuture.resultNow(), ordersFuture.resultNow());
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

// 使用結(jié)構(gòu)化并發(fā)處理多個(gè)API調(diào)用
try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
    var weatherFuture = scope.fork(() -> callWeatherAPI());
    var trafficFuture = scope.fork(() -> callTrafficAPI());
    var newsFuture = scope.fork(() -> callNewsAPI());
    
    try {
        scope.join();
        scope.throwIfFailed();
        
        // 所有API調(diào)用成功，處理結(jié)果
        var dashboard = createDashboard(
            weatherFuture.resultNow(),
            trafficFuture.resultNow(),
            newsFuture.resultNow()
        );
        return dashboard;
    } catch (Exception e) {
        // 有一個(gè)API調(diào)用失敗，所有任務(wù)都被取消
        return createFallbackDashboard();
    }
}

// 定義一些記錄
record Point(int x, int y) {}
record Rectangle(Point topLeft, Point bottomRight) {}
record Circle(Point center, int radius) {}

// 使用傳統(tǒng)方式處理記錄
Object shape = new Rectangle(new Point(1, 2), new Point(5, 6));
if (shape instanceof Rectangle) {
    Rectangle r = (Rectangle) shape;
    Point topLeft = r.topLeft();
    Point bottomRight = r.bottomRight();
    int width = bottomRight.x() - topLeft.x();
    int height = bottomRight.y() - topLeft.y();
    System.out.println("Rectangle with width " + width + " and height " + height);
}

// 使用Record模式解構(gòu)
if (shape instanceof Rectangle(Point(var x1, var y1), Point(var x2, var y2))) {
    int width = x2 - x1;
    int height = y2 - y1;
    System.out.println("Rectangle with width " + width + " and height " + height);
}

// 結(jié)合switch使用
String getDescription(Object shape) {
    return switch (shape) {
        case Rectangle(Point(var x1, var y1), Point(var x2, var y2)) ->
            "Rectangle from (%d,%d) to (%d,%d)".formatted(x1, y1, x2, y2);
        
        case Circle(Point(var x, var y), var r) ->
            "Circle at (%d,%d) with radius %d".formatted(x, y, r);
        
        default -> "Unknown shape";
    };
}

// 傳統(tǒng)方式
String name = "Alice";
int age = 30;
String message = "Hello, " + name + "! Next year, you'll be " + (age + 1) + ".";

// 使用字符串模板
String message = STR."Hello, {name}! Next year, you'll be {age + 1}.";

// 帶表達(dá)式的模板
String status = "active";
String message = STR."User status: {status.toUpperCase()} (set {LocalDate.now()})";

// 格式化數(shù)字
double value = 1234.56789;
String formatted = STR."The value is {value%.2f}";  // "The value is 1234.57"

// 多行JSON
String json = STR."""
    {
      "name": "{name}",
      "age": {age},
      "isAdult": {age >= 18},
      "contacts": [
        {generateContactsJson()}
      ]
    }
    """;

// 序列化集合基本用法
SequencedCollection<String> names = new ArrayList<>(List.of("Alice", "Bob", "Charlie"));

// 獲取第一個(gè)和最后一個(gè)元素
String first = names.getFirst();  // "Alice"
String last = names.getLast();    // "Charlie"

// 添加元素到兩端
names.addFirst("Zoe");
names.addLast("David");
System.out.println(names);  // [Zoe, Alice, Bob, Charlie, David]

// 創(chuàng)建反向視圖
SequencedCollection<String> reversed = names.reversed();
System.out.println(reversed);  // [David, Charlie, Bob, Alice, Zoe]

// 序列化Map
SequencedMap<String, Integer> scores = new LinkedHashMap<>();
scores.put("Alice", 95);
scores.put("Bob", 85);
scores.put("Charlie", 90);

// 獲取第一個(gè)和最后一個(gè)條目
Map.Entry<String, Integer> firstEntry = scores.firstEntry();  // Alice=95
Map.Entry<String, Integer> lastEntry = scores.lastEntry();    // Charlie=90

// 添加條目到兩端
scores.putFirst("Zoe", 100);
scores.putLast("David", 80);

// 獲取鍵或值的序列化視圖
SequencedCollection<String> keys = scores.sequencedKeySet();
SequencedCollection<Integer> values = scores.sequencedValues();