redundant null-checks popped and constructor with create()-design

CityDoctorParent/Extensions/CityDoctorHealer/src/main/java/de/hft/stuttgart/citydoctor2/healing/SweepEdge.java

@@ -11,33 +11,34 @@ public class SweepEdge {
 	private Edge outgoingEdge;
 	private Vector3d referencePoint;
 	private UnitVector3d direction;
-	private boolean valid = false;
 	
-	public SweepEdge(Edge outgoingEdge, Vertex sweepVertex, double minSweepEdgeLength) {
+	public static SweepEdge create(Edge outgoingEdge, Vertex sweepVertex, double minSweepEdgeLength) {
 		
 		if (outgoingEdge == null || sweepVertex == null) {
-			return;
+			throw new IllegalArgumentException("outgoingEdge and sweepVertex must not be null");
+		}
+		if (minSweepEdgeLength <= 0) {
+			throw new IllegalArgumentException("minSweepEdgeLength must be positive");
 		}
 		
 		Vertex referencePoint = outgoingEdge.getOppositeVertex(sweepVertex);
 		if (referencePoint == null) {
-			return;
+			return null;
 		}
 		
 		Vector3d edgeVector = sweepVertex.minus(referencePoint);
 		if (edgeVector.getLength() < minSweepEdgeLength) {
-			return;
+			return null;
 		}
 		
-		this.outgoingEdge = outgoingEdge;
-		this.referencePoint = referencePoint;
-		this.direction = edgeVector.normalize();
-		this.valid = true;
+		return new SweepEdge(outgoingEdge, referencePoint, edgeVector.normalize());
 	}
 	
-	public boolean valid() {
-
-		return valid;
+	private SweepEdge(Edge outgoingEdge, Vector3d referencePoint, UnitVector3d direction) {
+		
+		this.outgoingEdge = outgoingEdge;
+		this.referencePoint = referencePoint;
+		this.direction = direction;
 	}
 	
 	public Vector3d intersection(Plane plane, double minLinePlaneAngleRatio) {
@@ -53,7 +54,7 @@ public class SweepEdge {
 	
 	public boolean hasIntersectionPoint(Plane plane, double minLinePlaneAngleRatio) {
 		
-		if (!valid || plane == null) {
+		if (plane == null) {
 			return false;
 		}
 		
@@ -80,7 +81,7 @@ public class SweepEdge {
 	
 	public boolean isSweepableEdge(Vector3d intersectionPoint, double eps) {
 		
-		if (!valid || intersectionPoint == null) {
+		if (intersectionPoint == null) {
 			return false;
 		}
 		

CityDoctorParent/Extensions/CityDoctorHealer/src/main/java/de/hft/stuttgart/citydoctor2/healing/SweepUtilities.java

@@ -61,7 +61,7 @@ public class SweepUtilities {
 	
 	public boolean calculate() {
 		
-		if (sweepVertices == null || targetPlane == null) {
+		if (sweepVertices == null) {
 			return false;
 		}
 		

CityDoctorParent/Extensions/CityDoctorHealer/src/main/java/de/hft/stuttgart/citydoctor2/healing/SweepVertex.java

@@ -29,18 +29,21 @@ public class SweepVertex {
 	
 	private Vertex sweepVertex;
 	private Vector3d newPoint;
-    private List<Edge> outgoingEdges  = new LinkedList<>();// TODO ?ist diese Zuweisung stabil?
+    private List<Edge> outgoingEdges  = new LinkedList<>();
 	
 	public SweepVertex(Vertex v) {
 		
+		if (v == null) {
+			throw new IllegalArgumentException("sweepVertex must not be null");
+		}
 		sweepVertex = v;
 	}
 	
 	public void collectOutgoingEdges(Polygon errorPoly, double minSweepEdgeLength) {
 		
 		outgoingEdges.clear();
-		if (errorPoly == null || sweepVertex == null) {
-			logger.error("Cannot collect outgoing edges: polygon or vertex is null");
+		if (errorPoly == null) {
+			logger.error("Cannot collect outgoing edges: polygon is null");
 			status = SweepVertexStatus.ERROR;
 			return;
 		}
@@ -70,7 +73,7 @@ public class SweepVertex {
 	
 	public void initStatus (Plane targetPlane, double maxPointPlaneDistance) {
 		
-		if (targetPlane == null || sweepVertex == null) {
+		if (targetPlane == null) {
 			status = SweepVertexStatus.ERROR;
 			return;
 		}
@@ -119,7 +122,7 @@ public class SweepVertex {
 		
 		newPoint = null;
 		
-		if (targetPlane == null || sweepVertex == null) {
+		if (targetPlane == null) {
 			status = SweepVertexStatus.ERROR;
 			return;
 		}
@@ -136,7 +139,7 @@ public class SweepVertex {
 			return;
 			
 		case SWEEP:
-			if (outgoingEdges == null || outgoingEdges.size() != 1) {
+			if (outgoingEdges.size() != 1) {
 				status = SweepVertexStatus.ERROR;
 				return;
 			}
@@ -147,8 +150,8 @@ public class SweepVertex {
 				return;
 			}
 			
-			SweepEdge sweepEdge = new SweepEdge(outgoingEdge, sweepVertex, minSweepEdgeLength);
-			if (!sweepEdge.valid()) {
+			SweepEdge sweepEdge = SweepEdge.create(outgoingEdge, sweepVertex, minSweepEdgeLength);
+			if (sweepEdge == null) {
 				status = SweepVertexStatus.ERROR;
 				return;
 			}
@@ -181,7 +184,7 @@ public class SweepVertex {
 			return;
 		}
 		
-		if (sweepVertex == null || newPoint == null) {
+		if (newPoint == null) {
 			status = SweepVertexStatus.ERROR;
 			return;
 		}