package w8;  

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

public class Pair {

    // 泛型键值对 Pair
    static class PairInner<K, V> {
        private K key;
        private V value;

        public PairInner(K key, V value) {
            this.key = key;
            this.value = value;
        }

        // 交换方法
        public PairInner<V, K> swap() {
            return new PairInner<>(value, key);
        }

        public K getKey() {
            return key;
        }

        public V getValue() {
            return value;
        }
    }

    // 泛型缓存 Cache
    static class Cache<K, V> {
        private Map<K, V> map = new HashMap<>();

        public void put(K key, V value) {
            map.put(key, value);
        }

        public V get(K key) {
            return map.get(key);
        }

        public void remove(K key) {
            map.remove(key);
        }

        public void clear() {
            map.clear();
        }

        public boolean containsKey(K key) {
            return map.containsKey(key);
        }
    }

    // 主程序运行
    public static void main(String[] args) {
        // 测试 Pair
        PairInner<String, Integer> pair = new PairInner<>("成绩", 95);
        PairInner<Integer, String> swapped = pair.swap();
        System.out.println("交换前：" + pair.getKey() + " " + pair.getValue());
        System.out.println("交换后：" + swapped.getKey() + " " + swapped.getValue());

        // 测试 Cache
        Cache<String, String> cache = new Cache<>();
        cache.put("姓名", "张三");
        System.out.println("获取缓存：" + cache.get("姓名"));
    }
}