Stream replaced with for-loop

GUI/src/main/java/cz/fidentis/analyst/distance/DistanceAction.java

@@ -10,6 +10,7 @@ import cz.fidentis.analyst.visitors.face.HausdorffDistancePrioritized;
 import cz.fidentis.analyst.visitors.mesh.HausdorffDistance.Strategy;
 import java.awt.Color;
 import java.awt.event.ActionEvent;
+import java.util.Collection;
 import java.util.DoubleSummaryStatistics;
 import java.util.HashMap;
 import java.util.List;
@@ -142,15 +143,20 @@ public class DistanceAction extends ControlPanelAction {
         
         final Map<FeaturePointType, Double> featurePointWeights = new HashMap<>(faceWeights.size());
         for (final Map.Entry<FeaturePointType, Map<MeshFacet, Double>> fpWeights: faceWeights.entrySet()) {
-            featurePointWeights.put(
-                    fpWeights.getKey(),
-                    fpWeights.getValue()
-                            .values()
-                            .stream()
-                            .mapToDouble(weight -> weight)
-                            .average()
-                            .orElse(Double.NaN)
-            );
+            final Collection<Double> weightsList = fpWeights.getValue().values();
+            
+            final double average;
+            if (weightsList.isEmpty()) {
+                average = Double.NaN;
+            } else {
+                double sum = 0;
+                for (final double weight: weightsList) {
+                    sum += weight;
+                }
+                average = sum / weightsList.size();
+            }
+            
+            featurePointWeights.put(fpWeights.getKey(), average);
         }
         
         controlPanel.updateFeaturePointWeights(featurePointWeights);