diff --git a/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/LruCache.java b/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/LruCache.java
index 6b2efc7..297ed5b 100644
--- a/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/LruCache.java
+++ b/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/LruCache.java
@@ -1,9 +1,9 @@
 import java.util.*;
 
 public class LruCache<K,V> implements Map<K,V> {
-    private Map<K,V> map;
-    private PriorityQueue<Object> priorityQueue;
-    private Map<Object,Integer> counts;
+    private final Map<K,V> map;
+    private final PriorityQueue<K> priorityQueue;
+    private final Map<K,Integer> counts;
     private final int maxSize;
 
     public LruCache(int maxSize) {
@@ -34,9 +34,9 @@ public class LruCache<K,V> implements Map<K,V> {
 
     @Override
     public V get(Object key) {
-        counts.put(key, counts.getOrDefault(key, 0) + 1);
+        counts.put((K) key, counts.getOrDefault(key, 0) + 1);
         priorityQueue.remove(key);
-        priorityQueue.add(key);
+        priorityQueue.add((K) key);
         return map.get(key);
     }
 
diff --git a/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/Program.java b/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/Program.java
index c512665..d82de8c 100644
--- a/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/Program.java
+++ b/2025/01/cracking_code_interview_16_25_lru_cache/src/main/java/Program.java
@@ -1,20 +1,24 @@
+import java.io.PrintStream;
+
 public class Program {
     public static void main(String[] args) {
+        testLruCache(System.out);
+    }
+
+    private static void testLruCache(PrintStream ps) {
         var lruCache = new LruCache<>(2);
         lruCache.put(1, "one");
         lruCache.put(2, "two");
-
-        System.out.println("Element: " + lruCache.get(1));
-        System.out.println("Element: " + lruCache.get(1));
-        System.out.println("Element: " + lruCache.get(1));
+        ps.println("Element: " + lruCache.get(1));
+        ps.println("Element: " + lruCache.get(1));
+        ps.println("Element: " + lruCache.get(1));
 
         lruCache.put(3, "three");
-        System.out.println("Element: " + lruCache.get(2));
+        ps.println("Element: " + lruCache.get(2));
         lruCache.put(4, "four");
-        System.out.println("Element: " + lruCache.get(4));
-        System.out.println("Element: " + lruCache.get(3));
-        System.out.println("Element: " + lruCache.get(2));
-        System.out.println("Element: " + lruCache.get(1));
-
+        ps.println("Element: " + lruCache.get(4));
+        ps.println("Element: " + lruCache.get(3));
+        ps.println("Element: " + lruCache.get(2));
+        ps.println("Element: " + lruCache.get(1));
     }
 }