diff --git a/libraries-data/src/main/java/com/baeldung/storm/bolt/AggregatingBolt.java b/libraries-data/src/main/java/com/baeldung/storm/bolt/AggregatingBolt.java
index 555ba7e692..c7263cd8d5 100644
--- a/libraries-data/src/main/java/com/baeldung/storm/bolt/AggregatingBolt.java
+++ b/libraries-data/src/main/java/com/baeldung/storm/bolt/AggregatingBolt.java
@@ -14,7 +14,7 @@ import java.util.List;
 import java.util.Map;
 
 public class AggregatingBolt extends BaseWindowedBolt {
-    OutputCollector outputCollector;
+    private OutputCollector outputCollector;
     @Override
     public void prepare(Map stormConf, TopologyContext context, OutputCollector collector) {
         this.outputCollector = collector;
diff --git a/libraries-data/src/main/java/com/baeldung/storm/bolt/FileWritingBolt.java b/libraries-data/src/main/java/com/baeldung/storm/bolt/FileWritingBolt.java
index a35ff3aaf5..40ed72164d 100644
--- a/libraries-data/src/main/java/com/baeldung/storm/bolt/FileWritingBolt.java
+++ b/libraries-data/src/main/java/com/baeldung/storm/bolt/FileWritingBolt.java
@@ -4,7 +4,6 @@ import com.baeldung.storm.model.AggregatedWindow;
 import com.fasterxml.jackson.annotation.JsonAutoDetect;
 import com.fasterxml.jackson.annotation.PropertyAccessor;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.ObjectWriter;
 import org.apache.storm.task.OutputCollector;
 import org.apache.storm.task.TopologyContext;
 import org.apache.storm.topology.OutputFieldsDeclarer;
@@ -20,9 +19,9 @@ import java.util.Map;
 
 public class FileWritingBolt extends BaseRichBolt {
     public static Logger logger = LoggerFactory.getLogger(FileWritingBolt.class);
-    BufferedWriter writer;
-    String filePath;
-    ObjectMapper objectMapper;
+    private BufferedWriter writer;
+    private String filePath;
+    private ObjectMapper objectMapper;
     @Override
     public void prepare(Map map, TopologyContext topologyContext, OutputCollector outputCollector) {
         objectMapper = new ObjectMapper();
diff --git a/libraries-data/src/main/java/com/baeldung/storm/model/User.java b/libraries-data/src/main/java/com/baeldung/storm/model/User.java
index 62b9ac639b..eafbf0e1eb 100644
--- a/libraries-data/src/main/java/com/baeldung/storm/model/User.java
+++ b/libraries-data/src/main/java/com/baeldung/storm/model/User.java
@@ -1,10 +1,10 @@
 package com.baeldung.storm.model;
 
 public class User {
-    String username;
-    String password;
-    String email;
-    int age;
+    private String username;
+    private String password;
+    private String email;
+    private int age;
 
     public String getUsername() {
         return username;
diff --git a/libraries-data/src/main/java/com/baeldung/storm/spout/RandomIntSpout.java b/libraries-data/src/main/java/com/baeldung/storm/spout/RandomIntSpout.java
index 669eb4f897..4a8ef76598 100644
--- a/libraries-data/src/main/java/com/baeldung/storm/spout/RandomIntSpout.java
+++ b/libraries-data/src/main/java/com/baeldung/storm/spout/RandomIntSpout.java
@@ -13,8 +13,8 @@ import java.util.Random;
 
 public class RandomIntSpout extends BaseRichSpout {
 
-    Random random;
-    SpoutOutputCollector outputCollector;
+    private Random random;
+    private SpoutOutputCollector outputCollector;
 
     @Override
     public void open(Map map, TopologyContext topologyContext, SpoutOutputCollector spoutOutputCollector) {
diff --git a/libraries-data/src/main/java/com/baeldung/storm/spout/RandomNumberSpout.java b/libraries-data/src/main/java/com/baeldung/storm/spout/RandomNumberSpout.java
index 5d7d3cc53e..371a61720a 100644
--- a/libraries-data/src/main/java/com/baeldung/storm/spout/RandomNumberSpout.java
+++ b/libraries-data/src/main/java/com/baeldung/storm/spout/RandomNumberSpout.java
@@ -13,8 +13,8 @@ import java.util.Map;
 import java.util.Random;
 
 public class RandomNumberSpout extends BaseRichSpout {
-    Random random;
-    SpoutOutputCollector collector;
+    private Random random;
+    private SpoutOutputCollector collector;
 
     @Override
     public void open(Map map, TopologyContext topologyContext, SpoutOutputCollector spoutOutputCollector) {