public static Bitmap createBitmap(int width, int height, Config config)

public Bitmap.Config inPreferredConfig = Bitmap.Config.ARGB_8888;

private DiskLruCache mDiskLruCache;
private final Object mDiskCacheLock = new Object();
private boolean mDiskCacheStarting = true;
private static final int DISK_CACHE_SIZE = 1024 * 1024 * 10; // 10MB
private static final String DISK_CACHE_SUBDIR = "thumbnails";

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...
    // Initialize memory cache
    ...
    // Initialize disk cache on background thread
    File cacheDir = getDiskCacheDir(this, DISK_CACHE_SUBDIR);
    new InitDiskCacheTask().execute(cacheDir);
    ...
}

class InitDiskCacheTask extends AsyncTask<File, Void, Void> {
    @Override
    protected Void doInBackground(File... params) {
        synchronized (mDiskCacheLock) {
            File cacheDir = params[0];
            mDiskLruCache = DiskLruCache.open(cacheDir, DISK_CACHE_SIZE);
            mDiskCacheStarting = false; // Finished initialization
            mDiskCacheLock.notifyAll(); // Wake any waiting threads
        }
        return null;
    }
}

class BitmapWorkerTask extends AsyncTask<Integer, Void, Bitmap> {
    ...
    // Decode image in background.
    @Override
    protected Bitmap doInBackground(Integer... params) {
        final String imageKey = String.valueOf(params[0]);

        // Check disk cache in background thread
        Bitmap bitmap = getBitmapFromDiskCache(imageKey);

        if (bitmap == null) { // Not found in disk cache
            // Process as normal
            final Bitmap bitmap = decodeSampledBitmapFromResource(
                    getResources(), params[0], 100, 100));
        }

        // Add final bitmap to caches
        addBitmapToCache(imageKey, bitmap);

        return bitmap;
    }
    ...
}

public void addBitmapToCache(String key, Bitmap bitmap) {
    // Add to memory cache as before
    if (getBitmapFromMemCache(key) == null) {
        mMemoryCache.put(key, bitmap);
    }

    // Also add to disk cache
    synchronized (mDiskCacheLock) {
        if (mDiskLruCache != null && mDiskLruCache.get(key) == null) {
            mDiskLruCache.put(key, bitmap);
        }
    }
}

public Bitmap getBitmapFromDiskCache(String key) {
    synchronized (mDiskCacheLock) {
        // Wait while disk cache is started from background thread
        while (mDiskCacheStarting) {
            try {
                mDiskCacheLock.wait();
            } catch (InterruptedException e) {}
        }
        if (mDiskLruCache != null) {
            return mDiskLruCache.get(key);
        }
    }
    return null;
}

// Creates a unique subdirectory of the designated app cache directory. Tries to use external
// but if not mounted, falls back on internal storage.
public static File getDiskCacheDir(Context context, String uniqueName) {
    // Check if media is mounted or storage is built-in, if so, try and use external cache dir
    // otherwise use internal cache dir
    final String cachePath =
            Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) ||
                    !isExternalStorageRemovable() ? getExternalCacheDir(context).getPath() :
                            context.getCacheDir().getPath();

    return new File(cachePath + File.separator + uniqueName);
}

 public static ImageCache getInstance(
            FragmentManager fragmentManager, ImageCacheParams cacheParams) {

        // Search for, or create an instance of the non-UI RetainFragment
        final RetainFragment mRetainFragment = findOrCreateRetainFragment(fragmentManager);

        // See if we already have an ImageCache stored in RetainFragment
        ImageCache imageCache = (ImageCache) mRetainFragment.getObject();

        // No existing ImageCache, create one and store it in RetainFragment
        if (imageCache == null) {
            imageCache = new ImageCache(cacheParams);
            mRetainFragment.setObject(imageCache);
        }

        return imageCache;
 }

 private static RetainFragment findOrCreateRetainFragment(FragmentManager fm) {

        // Check to see if we have retained the worker fragment.
        RetainFragment mRetainFragment = (RetainFragment) fm.findFragmentByTag(TAG);

        // If not retained (or first time running), we need to create and add it.
        if (mRetainFragment == null) {
            mRetainFragment = new RetainFragment();
            fm.beginTransaction().add(mRetainFragment, TAG).commitAllowingStateLoss();
        }

        return mRetainFragment;

    }

    /**
     * A simple non-UI Fragment that stores a single Object and is retained over configuration
     * changes. It will be used to retain the ImageCache object.
     */
    public static class RetainFragment extends Fragment {
        private Object mObject;

        /**
         * Empty constructor as per the Fragment documentation
         */
        public RetainFragment() {}

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            // Make sure this Fragment is retained over a configuration change
            setRetainInstance(true);
        }

        /**
         * Store a single object in this Fragment.
         *
         * @param object The object to store
         */
        public void setObject(Object object) {
            mObject = object;
        }

        /**
         * Get the stored object.
         *
         * @return The stored object
         */
        public Object getObject() {
            return mObject;
        }
    }