From b2f08ed0a7b77bea0e3010eea7c4e8f8acf50c75 Mon Sep 17 00:00:00 2001
From: Jody Garnett <jody.garnett@gmail.com>
Date: Mon, 18 Feb 2019 14:25:38 -0800
Subject: [PATCH] Ask enforceArrayConsistency to copy provided array on
 modification

---
 .../geom/impl/CoordinateArraySequence.java    | 41 ++++++++++++++-----
 .../impl/CoordinateArraySequenceTest.java     |  4 +-
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/modules/core/src/main/java/org/locationtech/jts/geom/impl/CoordinateArraySequence.java b/modules/core/src/main/java/org/locationtech/jts/geom/impl/CoordinateArraySequence.java
index fef7107f73..d6134d68a2 100644
--- a/modules/core/src/main/java/org/locationtech/jts/geom/impl/CoordinateArraySequence.java
+++ b/modules/core/src/main/java/org/locationtech/jts/geom/impl/CoordinateArraySequence.java
@@ -12,6 +12,7 @@
 package org.locationtech.jts.geom.impl;
 
 import java.io.Serializable;
+import java.lang.reflect.Array;
 
 import org.locationtech.jts.geom.*;
 
@@ -82,13 +83,14 @@ public CoordinateArraySequence(Coordinate[] coordinates, int dimension) {
    */
   public CoordinateArraySequence(Coordinate[] coordinates, int dimension, int measures)
   {
-    this.coordinates = coordinates;
     this.dimension = dimension;
     this.measures = measures;
     if (coordinates == null) {
       this.coordinates = new Coordinate[0];
     }
-    enforceArrayConsistency( this.coordinates );
+    else {
+      this.coordinates = enforceArrayConsistency(coordinates);
+    }
   }
 
   /**
@@ -158,23 +160,42 @@ public CoordinateArraySequence(CoordinateSequence coordSeq)
 
   /**
    * Ensure array contents of the same type, making use of {@link #createCoordinate()} as needed.
+   * <p>
+   * A new array will be created if needed to return a consistent result.
+   * </p>
    * 
-   * @param array array is modified in place as needed
+   * @param array array containing consistent coordinate instances
    */
-  protected void enforceArrayConsistency(Coordinate[] array)
+  protected Coordinate[] enforceArrayConsistency(Coordinate[] array)
   {
      Coordinate sample = createCoordinate();
      Class<?> type = sample.getClass();
+     boolean isConsistent=true;
      for( int i = 0; i < array.length; i++) {
        Coordinate coordinate = array[i];
-       if( coordinate == null ) {
-         array[i] = createCoordinate();
+       if( coordinate != null && !coordinate.getClass().equals(type)) {
+         isConsistent = false;
+         break;
        }
-       else if(!coordinate.getClass().equals(type)) {
-         Coordinate duplicate = createCoordinate();
-         duplicate.setCoordinate(coordinate);
-         array[i] = duplicate;         
+     }
+     if( isConsistent ){
+       return array;
+     }
+     else {
+       Class<? extends Coordinate> coordinateType = sample.getClass();
+       Coordinate copy[] = (Coordinate[]) Array.newInstance(coordinateType, array.length);
+       for ( int i = 0; i < copy.length; i++){
+          Coordinate coordinate = array[i];
+          if( coordinate != null && !coordinate.getClass().equals(type)){
+            Coordinate duplicate = createCoordinate();
+            duplicate.setCoordinate(coordinate);
+            copy[i] = duplicate;
+          }
+          else {
+            copy[i] = coordinate;
+          }
        }
+       return copy;
      }
   }
 
diff --git a/modules/core/src/test/java/org/locationtech/jts/geom/impl/CoordinateArraySequenceTest.java b/modules/core/src/test/java/org/locationtech/jts/geom/impl/CoordinateArraySequenceTest.java
index a2e5f9176c..6aa19a96fa 100644
--- a/modules/core/src/test/java/org/locationtech/jts/geom/impl/CoordinateArraySequenceTest.java
+++ b/modules/core/src/test/java/org/locationtech/jts/geom/impl/CoordinateArraySequenceTest.java
@@ -178,13 +178,15 @@ public void testMixedCoordinates()
     Coordinate coord1 = new Coordinate(1.0,1.0,1.0);
     CoordinateXY coord2 = new CoordinateXY(2.0,2.0);
     CoordinateXYM coord3 = new CoordinateXYM(3.0,3.0,3.0);
-    Coordinate[] array = new Coordinate[] {coord1, coord2, coord3};
+    
+    Coordinate[] array = new Coordinate[] {coord1, coord2, coord3, null};
     CoordinateSequence seq = factory.create(array);
     assertEquals( 3, seq.getDimension());
     assertEquals( 1, seq.getMeasures());
     assertTrue( coord1.equals( seq.getCoordinate(0)));
     assertTrue( coord2.equals( seq.getCoordinate(1)));
     assertTrue( coord3.equals( seq.getCoordinate(2)));   
+    assertNull( seq.getCoordinate(3));   
   }
   
   private void initProgression(CoordinateSequence seq) {