added null-safety to BearingWithConfidenceCluster clients

java/com.sap.sailing.domain/src/com/sap/sailing/domain/base/BearingWithConfidence.java

@@ -6,5 +6,4 @@ import com.sap.sailing.domain.confidence.HasConfidenceAndIsScalable;
 
 
 public interface BearingWithConfidence<RelativeTo> extends HasConfidenceAndIsScalable<Pair<Double, Double>, Bearing, RelativeTo> {
-    Bearing getObject();
 }

java/com.sap.sailing.domain/src/com/sap/sailing/domain/confidence/ConfidenceBasedAverager.java

@@ -2,9 +2,15 @@ package com.sap.sailing.domain.confidence;
 
 public interface ConfidenceBasedAverager<ValueType, BaseType, RelativeTo> {
     /**
-     * If a non-<code>null</code> weigher has been set for this averager, <code>at</code> must be a valid
-     * reference point to which the weigher will determine the difference and from it the confidence for each
-     * of the <code>values</code>. Otherwise, the <code>at</code> argument is ignored.
+     * If a non-<code>null</code> weigher has been set for this averager, <code>at</code> must be a valid reference
+     * point to which the weigher will determine the difference and from it the confidence for each of the
+     * <code>values</code>. Otherwise, the <code>at</code> argument is ignored.
+     * 
+     * @return <code>null</code> if <code>values==null</code> or <code>values</code> is empty; otherwise, a non-
+     *         <code>null</code> average with confidence is returned. Note, however, that the
+     *         {@link HasConfidence#getObject() object} in the {@link HasConfidence} result may be <code>null</code>,
+     *         e.g., if the combined confidence went to 0.0 and the averager was unable to determine a reasonable
+     *         average value.
      */
     HasConfidence<ValueType, BaseType, RelativeTo> getAverage(
             Iterable<? extends HasConfidenceAndIsScalable<ValueType, BaseType, RelativeTo>> values, RelativeTo at);

java/com.sap.sailing.domain/src/com/sap/sailing/domain/confidence/ConfidenceFactory.java

@@ -12,6 +12,7 @@ public interface ConfidenceFactory {
      */
     <ValueType, BaseType, RelativeTo> ConfidenceBasedAverager<ValueType, BaseType, RelativeTo> createAverager(Weigher<RelativeTo> weigher);
     
+    <RelativeTo> Weigher<RelativeTo> createConstantWeigher(double constantConfidence);
     /**
      * Creates a weigher for time points. With increasing time difference the weight/confidence decreases exponentially.
      * It is halved every <code>halfConfidenceAfterMilliseconds</code> milliseconds.

java/com.sap.sailing.domain/src/com/sap/sailing/domain/confidence/impl/ConfidenceBasedAveragerFactoryImpl.java

@@ -6,6 +6,16 @@ import com.sap.sailing.domain.confidence.ConfidenceFactory;
 import com.sap.sailing.domain.confidence.Weigher;
 
 public class ConfidenceBasedAveragerFactoryImpl implements ConfidenceFactory {
+    @Override
+    public <RelativeTo> Weigher<RelativeTo> createConstantWeigher(final double constantConfidence) {
+        return new Weigher<RelativeTo>() {
+            @Override
+            public double getConfidence(RelativeTo fix, RelativeTo request) {
+                return constantConfidence;
+            }
+        };
+    }
+
     @Override
     public <ValueType, BaseType, RelativeTo> ConfidenceBasedAverager<ValueType, BaseType, RelativeTo> createAverager(Weigher<RelativeTo> weigher) {
         return new ConfidenceBasedAveragerImpl<ValueType, BaseType, RelativeTo>(weigher);

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/BearingWithConfidenceCluster.java

@@ -122,7 +122,9 @@ public class BearingWithConfidenceCluster<RelativeTo> {
     
     /**
      * If the cluster contains no bearings, <code>null</code> is returned. Otherwise, the average angle is computed
-     * by adding up the sin and cos values of the individual bearings, then computing the atan2 of the ratio.
+     * by adding up the sin and cos values of the individual bearings, then computing the atan2 of the ratio. If the
+     * combined confidence of the bearings in the cluster is 0.0, the result will contain <code>null</code> as
+     * {@link BearingWithConfidence#getObject() object}.
      */
     public BearingWithConfidence<RelativeTo> getAverage(RelativeTo relativeTo) {
         ConfidenceBasedAverager<Pair<Double, Double>, Bearing, RelativeTo> averager = ConfidenceFactory.INSTANCE.createAverager(weigher);
@@ -132,12 +134,13 @@ public class BearingWithConfidenceCluster<RelativeTo> {
     
     /**
      * Absolute difference to {@link #getAverage() this cluster's average bearing} in degrees. If there is no bearing stored in
-     * this cluster yet, 0.0 is returned.
+     * this cluster yet, or the combined confidence of the values in the cluster is 0.0,  0.0 is returned.
      * 
      * @return a value <code>&gt;=0.0</code>
      */
     private double getDifferenceFromAverage(Bearing bearing, RelativeTo relativeTo) {
-        return bearings.size() == 0 ? 0.0 : Math.abs(getAverage(relativeTo).getObject().getDifferenceTo(bearing).getDegrees());
+        Bearing averageBearing = getAverage(relativeTo).getObject();
+        return averageBearing == null ? 0.0 : Math.abs(averageBearing.getDifferenceTo(bearing).getDegrees());
     }
     
     protected Iterable<BearingWithConfidence<RelativeTo>> getBearings() {

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/DynamicGPSFixMovingTrackImpl.java

@@ -5,6 +5,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.NavigableSet;
 
+import com.sap.sailing.domain.base.BearingWithConfidence;
 import com.sap.sailing.domain.base.SpeedWithBearing;
 import com.sap.sailing.domain.base.impl.BearingWithConfidenceImpl;
 import com.sap.sailing.domain.base.impl.KnotSpeedWithBearingImpl;
@@ -75,7 +76,8 @@ public class DynamicGPSFixMovingTrackImpl<ItemType> extends DynamicTrackImpl<Ite
                 last = next;
             }
         }
-        Bearing bearing = bearingCluster.getAverage(at).getObject();
+        BearingWithConfidence<TimePoint> average = bearingCluster.getAverage(at);
+        Bearing bearing = average == null ? null : average.getObject();
         SpeedWithBearing avgSpeed = (count == 0 || bearing == null) ? null : new KnotSpeedWithBearingImpl(knotSum / count, bearing);
         return avgSpeed;
     }

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/GPSFixTrackImpl.java

@@ -8,6 +8,7 @@ import java.util.List;
 import java.util.NavigableSet;
 import java.util.Set;
 
+import com.sap.sailing.domain.base.BearingWithConfidence;
 import com.sap.sailing.domain.base.SpeedWithBearing;
 import com.sap.sailing.domain.base.impl.BearingWithConfidenceImpl;
 import com.sap.sailing.domain.base.impl.KnotSpeedImpl;
@@ -342,7 +343,8 @@ public class GPSFixTrackImpl<ItemType, FixType extends GPSFix> extends TrackImpl
             }
         }
         // TODO bug #169: return SpeedWithBearingWithConfidence to reflect the confidence reduction incurred by the difference of the fix's time point and "at"
-        Bearing bearing = bearingCluster.getAverage(at).getObject();
+        BearingWithConfidence<TimePoint> average = bearingCluster.getAverage(at);
+        Bearing bearing = average == null ? null : average.getObject();
         SpeedWithBearing avgSpeed = (count == 0 || bearing == null) ? null : new KnotSpeedWithBearingImpl(knotSum / count, bearing);
         return avgSpeed;
     }

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/WindTrackImpl.java

@@ -7,6 +7,7 @@ import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import com.sap.sailing.domain.base.BearingWithConfidence;
 import com.sap.sailing.domain.base.CourseChange;
 import com.sap.sailing.domain.base.SpeedWithBearing;
 import com.sap.sailing.domain.base.Timed;
@@ -134,6 +135,7 @@ public class WindTrackImpl extends TrackImpl<Wind> implements WindTrack {
         double knotSum = 0;
         // TODO bug #169: also measure speed with confidence; return confidence
         Weigher<TimePoint> weigher = ConfidenceFactory.INSTANCE.createLinearTimeDifferenceWeigher(millisecondsOverWhichToAverage);
+        // Weigher<TimePoint> weigher = ConfidenceFactory.INSTANCE.createConstantWeigher(1.0);
         BearingWithConfidenceCluster<TimePoint> bearingCluster = new BearingWithConfidenceCluster<TimePoint>(weigher);
         int count = 0;
         long beforeDistanceToAt = 0;
@@ -189,7 +191,8 @@ public class WindTrackImpl extends TrackImpl<Wind> implements WindTrack {
             return null;
         } else {
             // TODO bug #169: pass on confidence
-            SpeedWithBearing avgWindSpeed = new KnotSpeedWithBearingImpl(knotSum / count, bearingCluster.getAverage(at).getObject());
+            BearingWithConfidence<TimePoint> average = bearingCluster.getAverage(at);
+            SpeedWithBearing avgWindSpeed = new KnotSpeedWithBearingImpl(knotSum / count, average == null ? null : average.getObject());
             return new WindImpl(p, at, avgWindSpeed);
         }
     }