在 Java 8 中函数式编程的最佳实践有哪些？

// 匿名类
Runnable runnable = new Runnable() {
    @Override
    public void run() {
        System.out.println("Hello, world!");
    }
};
// Lambda 表达式
Runnable lambda = () -> System.out.println("Hello, world!");

Predicate<Integer> isEven = n -> n % 2 == 0;
Predicate<Integer> isGreaterThan10 = n -> n > 10;

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
// 使用函数组合筛选数字
List<Integer> evenAndGreaterThan10 = numbers.stream()
    .filter(isEven)
    .filter(isGreaterThan10)
    .collect(Collectors.toList());

List<Integer> doubled = numbers.stream()
    .map(n -> n * 2)
    .collect(Collectors.toList());

// Lambda 表达式
List<Integer> sorted = numbers.stream()
    .sorted((n1, n2) -> n1 - n2)
    .collect(Collectors.toList());
// 方法引用
List<Integer> sorted = numbers.stream()
    .sorted(Integer::compareTo)
    .collect(Collectors.toList());

List<Integer> immutableList = Collections.unmodifiableList(numbers);
immutableList.add(11); // 会抛出 UnsupportedOperationException

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
List<Integer> squared = new ArrayList<>();

for (Integer number : numbers) {
    int square = number * number;
    if (square < 20) {
        squared.add(square);
    }
}

List<Integer> squared = numbers.stream()
    .map(n -> n * n)
    .filter(n -> n < 20)
    .collect(Collectors.toList());