一文详解Java17中LinkedList类的用法和应用场景

import java.util.LinkedList;
 
public class LinkedListDemo {
    public static void main(String[] args) {
        var list = new LinkedList<String>(); // 类型推断（Java 10+）
 
        // 添加元素（支持链式调用）
        list.add("A")
            .addFirst("B")
            .addLast("C")
            .add(1, "D");
        System.out.println("初始化后: " + list); // 输出: [B, D, A, C]
 
        // 删除元素（结合 Lambda 表达式）
        list.removeIf(s -> s.equals("A")); // 删除 "A"
        System.out.println("删除后: " + list); // 输出: [B, D, C]
    }
}

var deque = new LinkedList<Integer>();
// 头部插入
deque.offerFirst(10);
// 尾部插入
deque.offerLast(20);
// 头部删除
System.out.println(deque.pollFirst()); // 输出: 10
// 尾部删除
System.out.println(deque.pollLast());  // 输出: 20

var numbers = new LinkedList<>(List.of(1, 2, 3, 4, 5));
 
// 过滤偶数并转换为字符串
List<String> result = numbers.stream()
    .filter(n -> n % 2 == 0)
    .map(Object::toString)
    .toList();
 
System.out.println(result); // 输出: [2, 4]

public class LRUCache<K, V> {
    private final LinkedList<K> accessOrder = new LinkedList<>();
    private final Map<K, V> cache = new HashMap<>();
    private final int capacity;
 
    public LRUCache(int capacity) {
        this.capacity = capacity;
    }
 
    public V get(K key) {
        if (cache.containsKey(key)) {
            accessOrder.remove(key);        // 移除旧位置
            accessOrder.addFirst(key);      // 更新为最近访问
            return cache.get(key);
        }
        return null;
    }
 
    public void put(K key, V value) {
        if (cache.size() >= capacity) {
            K oldest = accessOrder.removeLast(); // 删除最久未使用的键
            cache.remove(oldest);
        }
        accessOrder.addFirst(key);
        cache.put(key, value);
    }
}

list.forEach(System.out::println); // 推荐方式

var syncList = Collections.synchronizedList(new LinkedList<>());

Object element = list.getFirst();
switch (element) {
    case String s -> System.out.println("String: " + s);
    case Integer i -> System.out.println("Integer: " + i);
    default -> System.out.println("Unknown type");
}