4 files changed, 9 insertions, 9 deletions
diff --git a/src/main/java/org/traccar/helper/BitBuffer.java b/src/main/java/org/traccar/helper/BitBuffer.java
index f30a4557b..323807ba9 100644
--- a/src/main/java/org/traccar/helper/BitBuffer.java
+++ b/src/main/java/org/traccar/helper/BitBuffer.java
@@ -93,7 +93,7 @@ public class BitBuffer {
             return result;
         } else {
             result &= signBit - 1;
-            result += ~(signBit - 1);
+            result += -signBit;
             return result;
         }
     }
diff --git a/src/main/java/org/traccar/helper/Checksum.java b/src/main/java/org/traccar/helper/Checksum.java
index c1de983d8..8c3d0063a 100644
--- a/src/main/java/org/traccar/helper/Checksum.java
+++ b/src/main/java/org/traccar/helper/Checksum.java
@@ -26,12 +26,12 @@ public final class Checksum {
 
     public static class Algorithm {
 
-        private int poly;
-        private int init;
-        private boolean refIn;
-        private boolean refOut;
-        private int xorOut;
-        private int[] table;
+        private final int poly;
+        private final int init;
+        private final boolean refIn;
+        private final boolean refOut;
+        private final int xorOut;
+        private final int[] table;
 
         public Algorithm(int bits, int poly, int init, boolean refIn, boolean refOut, int xorOut) {
             this.poly = poly;
diff --git a/src/main/java/org/traccar/helper/DateBuilder.java b/src/main/java/org/traccar/helper/DateBuilder.java
index 9752f6977..24b7d027a 100644
--- a/src/main/java/org/traccar/helper/DateBuilder.java
+++ b/src/main/java/org/traccar/helper/DateBuilder.java
@@ -21,7 +21,7 @@ import java.util.TimeZone;
 
 public class DateBuilder {
 
-    private Calendar calendar;
+    private final Calendar calendar;
 
     public DateBuilder() {
         this(TimeZone.getTimeZone("UTC"));
diff --git a/src/main/java/org/traccar/helper/Parser.java b/src/main/java/org/traccar/helper/Parser.java
index 1471ec237..75106e2ba 100644
--- a/src/main/java/org/traccar/helper/Parser.java
+++ b/src/main/java/org/traccar/helper/Parser.java
@@ -242,7 +242,7 @@ public class Parser {
 
     public Date nextDateTime(DateTimeFormat format, String timeZone) {
         int year = 0, month = 0, day = 0;
-        int hour = 0, minute = 0, second = 0, millisecond = 0;
+        int hour, minute, second, millisecond = 0;
 
         switch (format) {
             case HMS: