diff --git a/core-java/src/main/java/com/baeldung/comparable/PlayerSorter.java b/core-java/src/main/java/com/baeldung/comparable/PlayerSorter.java
index 1f64a5eb43..eeb2c7a883 100644
--- a/core-java/src/main/java/com/baeldung/comparable/PlayerSorter.java
+++ b/core-java/src/main/java/com/baeldung/comparable/PlayerSorter.java
@@ -2,12 +2,13 @@ package com.baeldung.comparable;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 
 public class PlayerSorter {
 
     public static void main(String[] args) {
         
-        ArrayList<Player> footballTeam = new ArrayList<Player>();
+        List<Player> footballTeam = new ArrayList<Player>();
         Player player1 = new Player(59, "John", 20);
         Player player2 = new Player(67, "Roger", 22);
         Player player3 = new Player(45, "Steven", 24);
diff --git a/core-java/src/main/java/com/baeldung/comparator/PlayerAgeSorter.java b/core-java/src/main/java/com/baeldung/comparator/PlayerAgeSorter.java
index e7d3fd1264..3bbbcddb80 100644
--- a/core-java/src/main/java/com/baeldung/comparator/PlayerAgeSorter.java
+++ b/core-java/src/main/java/com/baeldung/comparator/PlayerAgeSorter.java
@@ -2,12 +2,13 @@ package com.baeldung.comparator;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 
 public class PlayerAgeSorter {
 
     public static void main(String[] args) {
         
-        ArrayList<Player> footballTeam = new ArrayList<Player>();
+        List<Player> footballTeam = new ArrayList<Player>();
         Player player1 = new Player(59, "John", 22);
         Player player2 = new Player(67, "Roger", 20);
         Player player3 = new Player(45, "Steven", 24);
diff --git a/core-java/src/main/java/com/baeldung/comparator/PlayerRankingSorter.java b/core-java/src/main/java/com/baeldung/comparator/PlayerRankingSorter.java
index a6a971f99e..581585fb7e 100644
--- a/core-java/src/main/java/com/baeldung/comparator/PlayerRankingSorter.java
+++ b/core-java/src/main/java/com/baeldung/comparator/PlayerRankingSorter.java
@@ -2,12 +2,13 @@ package com.baeldung.comparator;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 
 public class PlayerRankingSorter {
 
     public static void main(String[] args) {
         
-        ArrayList<Player> footballTeam = new ArrayList<Player>();
+        List<Player> footballTeam = new ArrayList<Player>();
         Player player1 = new Player(59, "John", 22);
         Player player2 = new Player(67, "Roger", 20);
         Player player3 = new Player(45, "Steven", 40);
diff --git a/core-java/src/test/java/com/baeldung/comparable/ComparableUnitTest.java b/core-java/src/test/java/com/baeldung/comparable/ComparableUnitTest.java
index c65c2c3740..2b45dd0391 100644
--- a/core-java/src/test/java/com/baeldung/comparable/ComparableUnitTest.java
+++ b/core-java/src/test/java/com/baeldung/comparable/ComparableUnitTest.java
@@ -4,6 +4,7 @@ import static org.junit.Assert.assertEquals;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 
 import org.junit.Test;
 
@@ -11,7 +12,7 @@ public class ComparableUnitTest {
     
     @Test
     public void whenUsingComparable_thenSortedList() {
-        ArrayList<Player> footballTeam = new ArrayList<Player>();
+        List<Player> footballTeam = new ArrayList<Player>();
         Player player1 = new Player(59, "John", 20);
         Player player2 = new Player(67, "Roger", 22);
         Player player3 = new Player(45, "Steven", 24);
diff --git a/core-java/src/test/java/com/baeldung/comparator/ComparatorUnitTest.java b/core-java/src/test/java/com/baeldung/comparator/ComparatorUnitTest.java
index 78f0e0bf33..769986edec 100644
--- a/core-java/src/test/java/com/baeldung/comparator/ComparatorUnitTest.java
+++ b/core-java/src/test/java/com/baeldung/comparator/ComparatorUnitTest.java
@@ -4,20 +4,28 @@ import static org.junit.Assert.assertEquals;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 
+import org.junit.Before;
 import org.junit.Test;
 
 public class ComparatorUnitTest {
     
-    @Test
-    public void whenUsingRankingComparator_thenSortedList() {
-        ArrayList<Player> footballTeam = new ArrayList<Player>();
+    List<Player> footballTeam;
+    
+    @Before
+    public void setUp(){
+        footballTeam = new ArrayList<Player>();
         Player player1 = new Player(59, "John", 20);
         Player player2 = new Player(67, "Roger", 22);
         Player player3 = new Player(45, "Steven", 24);
         footballTeam.add(player1);
         footballTeam.add(player2);
         footballTeam.add(player3);
+    }
+    
+    @Test
+    public void whenUsingRankingComparator_thenSortedList() {
         PlayerRankingComparator playerComparator = new PlayerRankingComparator();
         Collections.sort(footballTeam, playerComparator);
         assertEquals(footballTeam.get(0).getName(), "Steven");
@@ -26,13 +34,6 @@ public class ComparatorUnitTest {
     
     @Test
     public void whenUsingAgeComparator_thenSortedList() {
-        ArrayList<Player> footballTeam = new ArrayList<Player>();
-        Player player1 = new Player(59, "John", 20);
-        Player player2 = new Player(67, "Roger", 22);
-        Player player3 = new Player(45, "Steven", 24);
-        footballTeam.add(player1);
-        footballTeam.add(player2);
-        footballTeam.add(player3);
         PlayerAgeComparator playerComparator = new PlayerAgeComparator();
         Collections.sort(footballTeam, playerComparator);
         assertEquals(footballTeam.get(0).getName(), "John");