W8

W8/Cache.java

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+import java.util.HashMap;
+import java.util.Map;
+
+public class Cache<K, V> {
+    private final Map<K, V> cache;
+
+    public Cache() {
+        cache = new HashMap<>();
+    }
+
+    // 存入缓存
+    public void put(K key, V value) {
+        cache.put(key, value);
+    }
+
+    // 读取缓存
+    public V get(K key) {
+        return cache.get(key);
+    }
+
+    // 移除缓存
+    public V remove(K key) {
+        return cache.remove(key);
+    }
+
+    // 清空缓存
+    public void clear() {
+        cache.clear();
+    }
+
+    // 获取缓存大小
+    public int size() {
+        return cache.size();
+    }
+
+    // 测试
+    public static void main(String[] args) {
+        Cache<String, Integer> ageCache = new Cache<>();
+        ageCache.put("张三", 20);
+        ageCache.put("李四", 22);
+
+        System.out.println("张三的年龄：" + ageCache.get("张三"));
+        System.out.println("缓存大小：" + ageCache.size());
+
+        ageCache.remove("李四");
+        System.out.println("移除李四后缓存大小：" + ageCache.size());
+    }
+}

W8/Pair.java

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+public class Pair<K, V> {
+    private K key;
+    private V value;
+
+    // 构造方法
+    public Pair(K key, V value) {
+        this.key = key;
+        this.value = value;
+    }
+
+    // 交换方法：交换 key 和 value 的值
+    public Pair<V, K> swap() {
+        return new Pair<>(value, key);
+    }
+
+    // Getter/Setter
+    public K getKey() {
+        return key;
+    }
+
+    public void setKey(K key) {
+        this.key = key;
+    }
+
+    public V getValue() {
+        return value;
+    }
+
+    public void setValue(V value) {
+        this.value = value;
+    }
+
+    @Override
+    public String toString() {
+        return "Pair{" +
+                "key=" + key +
+                ", value=" + value +
+                '}';
+    }
+
+    // 测试
+    public static void main(String[] args) {
+        Pair<String, Integer> pair = new Pair<>("年龄", 20);
+        System.out.println("交换前：" + pair);
+        Pair<Integer, String> swapped = pair.swap();
+        System.out.println("交换后：" + swapped);
+    }
+}

W8/TestGeneric.java

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+import java.lang.reflect.Field;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.List;
+
+public class GenericReflectDemo {
+    // 成员变量带泛型
+    private List<String> list;
+
+    public static void main(String[] args) throws NoSuchFieldException {
+        // 1. 获取成员变量的泛型类型
+        Field field = GenericReflectDemo.class.getDeclaredField("list");
+        Type genericType = field.getGenericType();
+        if (genericType instanceof ParameterizedType) {
+            ParameterizedType pType = (ParameterizedType) genericType;
+            Type[] actualTypeArgs = pType.getActualTypeArguments();
+            for (Type arg : actualTypeArgs) {
+                System.out.println("泛型参数类型：" + arg); // 输出 class java.lang.String
+            }
+        }
+
+        // 2. 获取父类的泛型参数
+        class MyList extends ArrayList<String> {}
+        Type superType = MyList.class.getGenericSuperclass();
+        if (superType instanceof ParameterizedType) {
+            ParameterizedType pType = (ParameterizedType) superType;
+            System.out.println("父类泛型参数：" + pType.getActualTypeArguments()[0]);
+        }
+    }
+}