List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "Anna");

for (String name : names) {
    if (name.startsWith("A")) {
        System.out.println(name.toUpperCase());
    }
}

names.stream()
     .filter(name -> name.startsWith("A"))
     .map(String::toUpperCase)
     .forEach(System.out::println);

for (String item : list) {
    System.out.println(item); 
}

for (File file : files) {
    if (file.length() == 0) {
        isEmpty = true;
        break; // 發(fā)現(xiàn)空文件就立即停止
    }
}

for (Order order : orders) {
    // 復(fù)雜的業(yè)務(wù)判斷
    if (order.isValid() 
        && (order.isVip() || order.getAmount() > 1000)
        && !order.isCancelled()) {
        processOrder(order);
    }
}

int successCount = 0;
int failCount = 0;
List<Result> results = new ArrayList<>();
for (Task task : tasks) {
    try {
        Result result = executeTask(task);
        results.add(result);
        successCount++;
    } catch (Exception e) {
        failCount++;
        logger.error("任務(wù)執(zhí)行失敗", e);
    }
}

for (int i = 0; i < list.size(); i++) {
    if (i % 2 == 0) { // 每隔一個(gè)元素處理
        process(list.get(i));
    }
}

for (User user : users) {
    // 多個(gè)步驟，相互依賴
    Profile profile = buildProfile(user);
    validateProfile(profile);
    saveToDatabase(profile);
    sendNotification(user);
}

// 在游戲開發(fā)、算法競賽等場景
for (int i = 0; i < MAX_ITERATIONS; i++) {
    // 極其簡單的數(shù)學(xué)運(yùn)算
    result += array[i] * factor;
}

for (int i = 0; i < list.size(); i++) {
    if (shouldRemove(list.get(i))) {
        list.remove(i); // 直接修改原集合
        i--; // 調(diào)整索引
    }
}

List<Product> results = products.stream()
    .filter(p -> p.getStock() > 0)      // 過濾有庫存的
    .filter(p -> p.getPrice() < 100)    // 過濾價(jià)格小于100的
    .sorted(Comparator.comparing(Product::getPrice)) // 按價(jià)格排序
    .limit(10)                          // 只取前10個(gè)
    .collect(Collectors.toList());      // 收集結(jié)果

// 從員工列表中提取姓名
List<String> names = employees.stream()
    .map(Employee::getName)  // 提取姓名
    .collect(Collectors.toList());

// 復(fù)雜的統(tǒng)計(jì)一句搞定
DoubleSummaryStatistics stats = employees.stream()
    .mapToDouble(Employee::getSalary)
    .summaryStatistics();
System.out.println("平均工資: " + stats.getAverage());
System.out.println("最高工資: " + stats.getMax());
System.out.println("最低工資: " + stats.getMin());

// 按部門分組
Map<Department, List<Employee>> byDept = employees.stream()
    .collect(Collectors.groupingBy(Employee::getDepartment));
// 按條件分區(qū)
Map<Boolean, List<Employee>> partitioned = employees.stream()
    .collect(Collectors.partitioningBy(emp -> emp.getSalary() > 10000));

List<String> uniqueNames = employees.stream()
    .map(Employee::getName)
    .distinct()             // 去重
    .sorted()               // 排序
    .collect(Collectors.toList());

// 是否存在滿足條件的元素
boolean hasManager = employees.stream()
    .anyMatch(emp -> "經(jīng)理".equals(emp.getPosition()));
// 查找第一個(gè)滿足條件的
Optional<Employee> firstRich = employees.stream()
    .filter(emp -> emp.getSalary() > 50000)
    .findFirst();

// 將姓名用逗號(hào)拼接
String nameStr = employees.stream()
    .map(Employee::getName)
    .collect(Collectors.joining(", "));
// 數(shù)字求和
double totalSalary = employees.stream()
    .mapToDouble(Employee::getSalary)
    .sum();

List<String> results = bigList.parallelStream()
    .map(this::expensiveOperation) // 耗時(shí)操作
    .collect(Collectors.toList());

// 錯(cuò)誤示范！
int count = 0;
list.stream().forEach(item -> {
    if (item.isValid()) {
        count++; // 編譯報(bào)錯(cuò)！count 必須是 final 或 effectively final
    }
});

long count = list.stream().filter(Item::isValid).count();