diff --git a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/App.java b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/App.java
index 547392bb5671..e7b14249a732 100644
--- a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/App.java
+++ b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/App.java
@@ -60,7 +60,6 @@
 
 @Slf4j
 public class App {
-  private static final String BUBBLE = "Bubble ";
 
   static void noSpatialPartition(int numOfMovements, Map<Integer, Bubble> bubbles) {
     //all bubbles have to be checked for collision for all bubbles
diff --git a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/QuadTree.java b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/QuadTree.java
index 12a84f5a33e9..40c09a1d8f6e 100644
--- a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/QuadTree.java
+++ b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/QuadTree.java
@@ -25,7 +25,8 @@
 package com.iluwatar.spatialpartition;
 
 import java.util.Collection;
-import java.util.Hashtable;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * The quadtree data structure is being used to keep track of the objects' locations. It has the
@@ -37,7 +38,7 @@ public class QuadTree {
   Rect boundary;
   int capacity;
   boolean divided;
-  Hashtable<Integer, Point> points;
+  Map<Integer, Point> points;
   QuadTree northwest;
   QuadTree northeast;
   QuadTree southwest;
@@ -47,7 +48,7 @@ public class QuadTree {
     this.boundary = boundary;
     this.capacity = capacity;
     this.divided = false;
-    this.points = new Hashtable<>();
+    this.points = new HashMap<>();
     this.northwest = null;
     this.northeast = null;
     this.southwest = null;
diff --git a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionBubbles.java b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionBubbles.java
index 263ebb623a8c..3551f5ca3b9b 100644
--- a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionBubbles.java
+++ b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionBubbles.java
@@ -25,7 +25,6 @@
 package com.iluwatar.spatialpartition;
 
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.Map;
 
 /**
diff --git a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionGeneric.java b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionGeneric.java
index c1eb8d1f3600..7c03969a08e6 100644
--- a/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionGeneric.java
+++ b/spatial-partition/src/main/java/com/iluwatar/spatialpartition/SpatialPartitionGeneric.java
@@ -24,7 +24,7 @@
  */
 package com.iluwatar.spatialpartition;
 
-import java.util.Hashtable;
+import java.util.Map;
 
 /**
  * This abstract class has 2 fields, one of which is a hashtable containing all objects that
@@ -35,7 +35,7 @@
 
 public abstract class SpatialPartitionGeneric<T> {
 
-  Hashtable<Integer, T> playerPositions;
+  Map<Integer, T> playerPositions;
   QuadTree quadTree;
 
   /**