java/W8/Cache.java

import java.util.HashMap;
import java.util.Map;

public class Cache<K, V> {
    // 底层用 HashMap 存储数据
    private final Map<K, V> cacheMap;

    public Cache() {
        this.cacheMap = new HashMap<>();
    }

    // 存入缓存
    public void put(K key, V value) {
        cacheMap.put(key, value);
    }

    // 从缓存获取
    public V get(K key) {
        return cacheMap.get(key);
    }

    // 删除缓存
    public void remove(K key) {
        cacheMap.remove(key);
    }

    // 判断缓存是否包含某个 key
    public boolean containsKey(K key) {
        return cacheMap.containsKey(key);
    }

    // 清空缓存
    public void clear() {
        cacheMap.clear();
    }

    // 获取缓存大小
    public int size() {
        return cacheMap.size();
    }

    // 测试主方法
    public static void main(String[] args) {
        Cache<String, Integer> studentScoreCache = new Cache<>();

        // 存入数据
        studentScoreCache.put("张三", 90);
        studentScoreCache.put("李四", 85);
        studentScoreCache.put("王五", 95);

        // 查询数据
        System.out.println("张三的分数：" + studentScoreCache.get("张三"));
        System.out.println("缓存大小：" + studentScoreCache.size());

        // 删除数据
        studentScoreCache.remove("李四");
        System.out.println("删除李四后缓存大小：" + studentScoreCache.size());
        System.out.println("是否包含李四？" + studentScoreCache.containsKey("李四"));

        // 清空缓存
        studentScoreCache.clear();
        System.out.println("清空后缓存大小：" + studentScoreCache.size());
    }
}