import java.util.HashMap; import java.util.Map; public class Cache { private Map cache = new HashMap<>(); public void put(K key, V value) { cache.put(key, value); } public V get(K key) { return cache.get(key); } public void remove(K key) { cache.remove(key); } public void clear() { cache.clear(); } public int size() { return cache.size(); } public boolean containsKey(K key) { return cache.containsKey(key); } }