Hashtable<DecodeHintType, Object> hint = new Hashtable<DecodeHintType, Object>();
hint.put(DecodeHintType.TRY_HARDER, BarcodeFormat.QR_CODE);
the hastable needs to be imported by:
import com.google.zxing.common.flexdatatypes.HashTable;
But i didn't found flexdatatypes, not in zxing 2.1 o zxing 2.2