Use an Integer and a TimeUnit to define expiration timeout.

Android TimeExpiringLruCache.java

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import android.os.SystemClock;

/**
 * Least Recently Used cache with expiring items.
 *
 * @param <K> The key type
 * @param <V> The value type
 */
public class TimeExpiringLruCache<K, V> {
	
	public static final TimeUnit DefaultExpirationTimeUnit = TimeUnit.MINUTES;
	public static final int DefaultExpirationTimeout = 10;
	private int mExpirationTimeout;
	private TimeUnit mExpirationTimeUnit;

	
    private final LinkedHashMap<K, V> map;

    private final HashMap<K, Long>    validityTime;

    /** Size of this cache in units. Not necessarily the number of elements. */
    private int                       size;
    private final int                 maxSize;

    private int                       putCount;
    private int                       createCount;
    private int                       evictionCount;
    private int                       hitCount;
    private int                       missCount;


    /**
     * @param maxSize
     *            for caches that do not override {@link #sizeOf}, this is the maximum number of entries in the cache. For all other caches, this is
     *            the maximum sum of the sizes of the entries in this cache.
     * <p>
     * <b>Note</b>: Uses a default timeout of 10 minutes.
     */
    public TimeExpiringLruCache(final int maxSize) {
        if (maxSize <= 0) {
            throw new IllegalArgumentException("maxSize <= 0");
        }
        this.maxSize = maxSize;
        this.map = new LinkedHashMap<K, V>(0, 0.75f, true);
        this.validityTime = new HashMap<K, Long>(0, 0.75f);
        
		mExpirationTimeout = DefaultExpirationTimeout;
		mExpirationTimeUnit = DefaultExpirationTimeUnit;
    }
    
    /**
     * @param maxSize
     *            for caches that do not override {@link #sizeOf}, this is the maximum number of entries in the cache. For all other caches, this is
     *            the maximum sum of the sizes of the entries in this cache.
     * @param expirationTimeout
     *            timeout, after that period {@link TimeExpiringLruCache#get(Object)} will return null, and remove entry
     * @param expirationTimeUnit
     * 			  {@link TimeUnit} for the expiration timeout.
     */
    public TimeExpiringLruCache(final int maxSize, final int expirationTimeout, final TimeUnit expirationTimeUnit) {
    	this(maxSize);
		mExpirationTimeout = expirationTimeout;
		mExpirationTimeUnit = expirationTimeUnit;
    }

    /**
     * Calculates the expiration timeout in milliseconds.
     * @return {@link Long} value corresponding to the timeout.
     */
	private long getTimeoutInMillis() {
		return TimeUnit.MILLISECONDS.convert(mExpirationTimeout, mExpirationTimeUnit);
	}

    /**
     * Returns the value for {@code key} if it exists in the cache or can be created by {@code #create}. If a value was returned, it is moved to the
     * head of the queue. This returns null if a value is not cached and cannot be created.
     */
    public final V get(final K key) {
        if (key == null) {
            throw new NullPointerException("key == null");
        }

        V mapValue;
        synchronized (this) {
            mapValue = map.get(key);

            if (mapValue != null) {
                final boolean isValid = validityTime.get(key) > SystemClock.uptimeMillis();
                if (isValid) {
                    hitCount++;
                    return mapValue;
                } else {
                    remove(key);
                    mapValue = null;
                }
            }
            missCount++;
        }

        /*
         * Attempt to create a value. This may take a long time, and the map may be different when create() returns. If a conflicting value was added
         * to the map while create() was working, we leave that value in the map and release the created value.
         */

        final V createdValue = create(key);
        if (createdValue == null) {
            return null;
        }

        synchronized (this) {
            createCount++;
            mapValue = map.put(key, createdValue);
            final Long expirtyValue = validityTime.put(key, SystemClock.uptimeMillis() + getTimeoutInMillis());

            if (mapValue != null) {
                // There was a conflict so undo that last put
                map.put(key, mapValue);
                validityTime.put(key, expirtyValue);
            } else {
                size += safeSizeOf(key, createdValue);
            }
        }

        if (mapValue != null) {
            entryRemoved(false, key, createdValue, mapValue);
            return mapValue;
        } else {
            trimToSize(maxSize);
            return createdValue;
        }
    }
    
    /**
     * Gets all items which are not yet expired.
     * <p>
     * <b>Note</b>: Performs a query for all keys stored in the map. 
     * This will remove all expired items.
     * @return
     */
    public final List<V> getAllUnexpired() {
    	synchronized(this) {
    		HashSet<K> keySet = new HashSet<K>(map.keySet());
	    	for (K key : keySet) {
	    		get(key);
	    	}
	    	return new ArrayList<V>(map.values());
    	}
    }
    

    /**
     * Caches {@code value} for {@code key}. The value is moved to the head of the queue.
     * 
     * @return the previous value mapped by {@code key}.
     */
    public final V put(final K key, final V value) {
        if (key == null || value == null) {
            throw new NullPointerException("key == null || value == null");
        }

        V previous;
        synchronized (this) {
            putCount++;
            size += safeSizeOf(key, value);
            previous = map.put(key, value);
            if (previous != null) {
                size -= safeSizeOf(key, previous);
            }
            validityTime.put(key, SystemClock.uptimeMillis() + getTimeoutInMillis());
        }

        if (previous != null) {
            entryRemoved(false, key, previous, value);
        }

        trimToSize(maxSize);
        return previous;
    }

    /**
     * @param maxSize
     *            the maximum size of the cache before returning. May be -1 to evict even 0-sized elements.
     */
    private void trimToSize(final int maxSize) {
        while (true) {
            K key;
            V value;
            synchronized (this) {
                if (size < 0 || (map.isEmpty() && size != 0)) {
                    throw new IllegalStateException(getClass().getName()
                            + ".sizeOf() is reporting inconsistent results!");
                }

                if (size <= maxSize) {
                    break;
                }

                final Map.Entry<K, V> toEvict = map.entrySet().iterator().next();
                if (toEvict == null) {
                    break;
                }

                key = toEvict.getKey();
                value = toEvict.getValue();
                map.remove(key);
                size -= safeSizeOf(key, value);
                evictionCount++;
            }

            entryRemoved(true, key, value, null);
        }
    }

    /**
     * Removes the entry for {@code key} if it exists.
     * 
     * @return the previous value mapped by {@code key}.
     */
    public final V remove(final K key) {
        if (key == null) {
            throw new NullPointerException("key == null");
        }

        V previous;
        synchronized (this) {
            previous = map.remove(key);
            if (previous != null) {
                size -= safeSizeOf(key, previous);
                validityTime.remove(key);
            }
        }

        if (previous != null) {
            entryRemoved(false, key, previous, null);
        }

        return previous;
    }

    /**
     * Called for entries that have been evicted or removed. This method is invoked when a value is evicted to make space, removed by a call to
     * {@link #remove}, or replaced by a call to {@link #put}. The default implementation does nothing.
     * 
     * <p>
     * The method is called without synchronization: other threads may access the cache while this method is executing.
     * 
     * @param evicted
     *            true if the entry is being removed to make space, false if the removal was caused by a {@link #put} or {@link #remove}.
     * @param newValue
     *            the new value for {@code key}, if it exists. If non-null, this removal was caused by a {@link #put}. Otherwise it was caused by an
     *            eviction or a {@link #remove}.
     */
    protected void entryRemoved(final boolean evicted, final K key, final V oldValue, final V newValue) {
    }

    /**
     * Called after a cache miss to compute a value for the corresponding key. Returns the computed value or null if no value can be computed. The
     * default implementation returns null.
     * 
     * <p>
     * The method is called without synchronization: other threads may access the cache while this method is executing.
     * 
     * <p>
     * If a value for {@code key} exists in the cache when this method returns, the created value will be released with {@link #entryRemoved} and
     * discarded. This can occur when multiple threads request the same key at the same time (causing multiple values to be created), or when one
     * thread calls {@link #put} while another is creating a value for the same key.
     */
    protected V create(final K key) {
        return null;
    }

    private int safeSizeOf(final K key, final V value) {
        final int result = sizeOf(key, value);
        if (result < 0) {
            throw new IllegalStateException("Negative size: " + key + "=" + value);
        }
        return result;
    }

    /**
     * Returns the size of the entry for {@code key} and {@code value} in user-defined units. The default implementation returns 1 so that size is the
     * number of entries and max size is the maximum number of entries.
     * 
     * <p>
     * An entry's size must not change while it is in the cache.
     */
    protected int sizeOf(final K key, final V value) {
        return 1;
    }

    /**
     * Clear the cache, calling {@link #entryRemoved} on each removed entry.
     */
    public final void evictAll() {
        trimToSize(-1); // -1 will evict 0-sized elements
    }

    /**
     * For caches that do not override {@link #sizeOf}, this returns the number of entries in the cache. For all other caches, this returns the sum of
     * the sizes of the entries in this cache.
     */
    public synchronized final int size() {
        return size;
    }

    /**
     * For caches that do not override {@link #sizeOf}, this returns the maximum number of entries in the cache. For all other caches, this returns
     * the maximum sum of the sizes of the entries in this cache.
     */
    public synchronized final int maxSize() {
        return maxSize;
    }

    /**
     * Returns the number of times {@link #get} returned a value that was already present in the cache.
     */
    public synchronized final int hitCount() {
        return hitCount;
    }

    /**
     * Returns the number of times {@link #get} returned null or required a new value to be created.
     */
    public synchronized final int missCount() {
        return missCount;
    }

    /**
     * Returns the number of times {@link #create(Object)} returned a value.
     */
    public synchronized final int createCount() {
        return createCount;
    }

    /**
     * Returns the number of times {@link #put} was called.
     */
    public synchronized final int putCount() {
        return putCount;
    }

    /**
     * Returns the number of values that have been evicted.
     */
    public synchronized final int evictionCount() {
        return evictionCount;
    }

    /**
     * Returns a copy of the current contents of the cache, ordered from least recently accessed to most recently accessed.
     */
    public synchronized final Map<K, V> snapshot() {
        return new LinkedHashMap<K, V>(map);
    }

	@Override
    public synchronized final String toString() {
        final int accesses = hitCount + missCount;
        final int hitPercent = accesses != 0 ? (100 * hitCount / accesses) : 0;
        return String.format("LruCache[maxSize=%d,hits=%d,misses=%d,hitRate=%d%%]",
                maxSize, hitCount, missCount, hitPercent);
    }
}