Merge pull request #34 from oskopek/issue-32

Fix runtime detection exception when NP detected as null.

Fixes #32

carcv-core/src/main/java/org/carcv/impl/core/detect/NumberPlateDetectorImpl.java

@@ -28,6 +28,8 @@
 import org.carcv.core.detect.NumberPlateDetector;
 import org.carcv.core.model.AbstractCarImage;
 import org.carcv.impl.core.util.CollectionUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.xml.sax.SAXException;
 
 /**
@@ -39,6 +41,8 @@
  */
 public class NumberPlateDetectorImpl extends NumberPlateDetector {
 
+    final private static Logger LOGGER = LoggerFactory.getLogger(NumberPlateDetectorImpl.class);
+
     private static NumberPlateDetectorImpl detector;
     private Intelligence intel;
 
@@ -73,7 +77,12 @@ public String detect(final List<? extends AbstractCarImage> images) {
     public String detectPlateText(final List<? extends AbstractCarImage> images) {
         ArrayList<String> numberPlates = new ArrayList<>();
         for (AbstractCarImage image : images) {
-            numberPlates.add(intel.recognize(new CarSnapshot(image.getImage())));
+            String plate = intel.recognize(new CarSnapshot(image.getImage()));
+            if (plate == null) {
+                plate = "null";
+                LOGGER.warn("Plate on image ID {} wasn't detected, writing null.", image.getId());
+            }
+            numberPlates.add(plate);
         }
         return CollectionUtils.highestCountElement(numberPlates);
     }