import java.util.Collections;  import java.util.HashMap;  import java.util.Map;  import java.util.concurrent.ExecutorService;  import java.util.concurrent.Executors;  import java.util.concurrent.TimeUnit;  public class SimpleCache<T> {   private final Map<String, T> m_objects;   private final Map<String, Long> m_expiredObjects;   private final long m_lExpireTime;   private final ExecutorService m_executor;   public SimpleCache() {    this(500);   }   public SimpleCache(final int nExpireTime) {    m_objects = Collections.synchronizedMap(new HashMap<String, T>());    m_expiredObjects = Collections.synchronizedMap(new HashMap<String, Long>());    m_lExpireTime = nExpireTime;    m_executor = Executors.newFixedThreadPool(256);    Executors.newScheduledThreadPool(5).scheduleWithFixedDelay(RemoveExpiredObjects(), m_lExpireTime / 2,      m_lExpireTime, TimeUnit.SECONDS);   }   private final Runnable RemoveExpiredObjects() {    return new Runnable() {     public void run() {      for (final String name : m_expiredObjects.keySet()) {       if (System.currentTimeMillis() > m_expiredObjects.get(name)) {        m_executor.execute(CreateRemoveRunnable(name));       }      }     }    };   }   private final Runnable CreateRemoveRunnable(final String name) {    return new Runnable() {     public void run() {      m_objects.remove(name);      m_expiredObjects.remove(name);     }    };   }   public long GetExpireTime() {    return m_lExpireTime;   }   public void Put(final String name, final T obj) {    Put(name, obj, m_lExpireTime);   }   public void Put(final String name, final T obj, final long expireTime) {    m_objects.put(name, obj);    m_expiredObjects.put(name, System.currentTimeMillis() + expireTime * 1000);   }   public T Get(final String name) {    final Long expireTime = m_expiredObjects.get(name);    if (expireTime == null)     return null;    if (System.currentTimeMillis() > expireTime) {     m_executor.execute(CreateRemoveRunnable(name));     return null;    }    return m_objects.get(name);   }   @SuppressWarnings("unchecked")   public <R extends T> R Get(final String name, final Class<R> type) {    return (R) Get(name);   }  }