jaitools-223

diff --git a/utils/src/main/java/org/jaitools/tilecache/DiskMemTileCache.java b/utils/src/main/java/org/jaitools/tilecache/DiskMemTileCache.java
index dd31efa..da8c190 100644
--- a/utils/src/main/java/org/jaitools/tilecache/DiskMemTileCache.java
+++ b/utils/src/main/java/org/jaitools/tilecache/DiskMemTileCache.java
@@ -338,6 +338,17 @@ public class DiskMemTileCache extends Observable implements TileCache {
     }
 
     /**
+     * Provides a hint that this object will not be used any longer.
+     * The results of accessing the object after a call to dispose()
+     * are undefined.
+     */
+    public void dispose() {
+        stopTilePolling();
+        // destroy the polling thread
+        tilePollingService.shutdown();
+    }
+
+    /**
      * Adds a tile to the cache if not already present.
      *
      * @param owner the image that this tile belongs to
diff --git a/utils/src/main/java/org/jaitools/tiledimage/DiskMemImage.java b/utils/src/main/java/org/jaitools/tiledimage/DiskMemImage.java
index 7d9229d..f039b27 100644
--- a/utils/src/main/java/org/jaitools/tiledimage/DiskMemImage.java
+++ b/utils/src/main/java/org/jaitools/tiledimage/DiskMemImage.java
@@ -330,6 +330,21 @@ public class DiskMemImage
     }
 
     /**
+     * Provides a hint that this object will not be used any longer.
+     * The results of accessing the object after a call to dispose()
+     * are undefined.
+     */
+    @Override
+    public void dispose() {
+        super.dispose();
+
+        if (!isUsingCommonCache() && tileCache != null) {
+            tileCache.dispose();
+            tileCache = null;
+        }
+    }
+
+    /**
      * Gets a tile for reading. Any changes to the tile's data
      * will not be preserved by the cache.
      *