diff --git a/src/main/java/ua/net/uid/utils/comparators/ComparableComparator.java b/src/main/java/ua/net/uid/utils/comparators/ComparableComparator.java
new file mode 100644
index 0000000..479b5cb
--- /dev/null
+++ b/src/main/java/ua/net/uid/utils/comparators/ComparableComparator.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2019 nightfall.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ua.net.uid.utils.comparators;
+
+import java.util.Comparator;
+
+class ComparableComparator<T extends Comparable<? super T>> implements Comparator<T>  {
+    private final boolean nullFirst;
+
+    public ComparableComparator(boolean nullFirst) { this.nullFirst = nullFirst; }
+    public ComparableComparator() { this(true); }
+
+    @Override
+    public int compare(T o1, T o2) {
+        if (o1 == o2) return 0;
+        if (o1 == null) return nullFirst ? -1 : 1;
+        if (o2 == null) return nullFirst ? 1 : -1;
+        return o1.compareTo(o2);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/ua/net/uid/utils/comparators/NullComparator.java b/src/main/java/ua/net/uid/utils/comparators/NullComparator.java
new file mode 100644
index 0000000..0e8a2d0
--- /dev/null
+++ b/src/main/java/ua/net/uid/utils/comparators/NullComparator.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2019 nightfall.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ua.net.uid.utils.comparators;
+
+import java.util.Comparator;
+
+class NullComparator<T> implements Comparator<T>  {
+    private final Comparator<? super T> notNullComparator;
+    private final boolean nullFirst;
+
+    public NullComparator(Comparator<? super T> notNullComparator, boolean nullFirst) {
+        this.notNullComparator = notNullComparator;
+        this.nullFirst = nullFirst;
+    }
+    public NullComparator(Comparator<T> notNullComparator) { this(notNullComparator, true); }
+
+    @Override
+    public int compare(T o1, T o2) {
+        if (o1 == o2) return 0;
+        if (o1 == null) return nullFirst ? -1 : 1;
+        if (o2 == null) return nullFirst ? 1 : -1;
+        return notNullComparator.compare(o1, o2);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/ua/net/uid/utils/comparators/NumberComparator.java b/src/main/java/ua/net/uid/utils/comparators/NumberComparator.java
index 1a65b4e..8f228ef 100644
--- a/src/main/java/ua/net/uid/utils/comparators/NumberComparator.java
+++ b/src/main/java/ua/net/uid/utils/comparators/NumberComparator.java
@@ -22,7 +22,7 @@
 import java.util.concurrent.atomic.AtomicLong;
 
 /**
- *
+ * 
  * @author nightfall
  */
 public class NumberComparator implements Comparator<Number> {
@@ -33,13 +33,13 @@
     private NumberComparator() {}
     
     @Override
+    //@SuppressWarnings("unchecked")
     public int compare(Number o1, Number o2) {
         if (o1 == o2) return 0;
         if (o1 == null) return -1;
         if (o2 == null) return 1;
-        if (o1.getClass() == o2.getClass() && o1 instanceof Comparable) 
-            return ((Comparable) o1).compareTo((Comparable) o2);
-        
+        if (o1.getClass().equals(o2.getClass()) && o1 instanceof Comparable)
+            return cmp(Comparable.class.cast(o1), Comparable.class.cast(o2));
         if (o1 instanceof BigDecimal) return compareBig((BigDecimal)o1, o2);
         if (o2 instanceof BigDecimal) return -compareBig((BigDecimal) o2, o1);
         if (o1 instanceof BigInteger) return compareBig((BigInteger) o1, o2);
@@ -47,7 +47,11 @@
 
         return isInteger(o1) && isInteger(o2)
             ? Long.compare(o1.longValue(), o1.longValue())
-            : Double.compare(o1.floatValue(), o2.floatValue());
+            : Double.compare(o1.doubleValue(), o2.doubleValue());
+    }
+
+    private static <T extends Comparable<? super T>> int cmp(T o1, T o2) {
+        return o1.compareTo(o2);
     }
 
     private static boolean isInteger(Number val) {
diff --git a/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java b/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java
index e97d3ad..9c7af9f 100644
--- a/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java
+++ b/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java
@@ -104,7 +104,8 @@
         return result;
     }
 
-    public <T> T minBy(Comparator<? super T> comparator, T ... items) {
+    @SafeVarargs
+    public static <T> T minBy(Comparator<? super T> comparator, T ... items) {
         T result = null;
         if (!isEmpty(items)) {
             for (T item : items)
@@ -114,7 +115,8 @@
         return result;
     }
 
-    public <T> T maxBy(Comparator<? super T> comparator, T ... items) {
+    @SafeVarargs
+    public static <T> T maxBy(Comparator<? super T> comparator, T ... items) {
         T result = null;
         if (!isEmpty(items)) {
             for (T item : items)
diff --git a/src/main/java/ua/net/uid/utils/time/DailyEquation.java b/src/main/java/ua/net/uid/utils/time/DailyEquation.java
index 4b31cdb..23f8154 100644
--- a/src/main/java/ua/net/uid/utils/time/DailyEquation.java
+++ b/src/main/java/ua/net/uid/utils/time/DailyEquation.java
@@ -20,8 +20,6 @@
  * 
  * https://www.aa.quae.nl/en/reken/zonpositie.html
  * 
- * TODO: переделать под java.time
- * 
  * @author nightfall
  */
 public class DailyEquation {
diff --git a/src/test/java/ua/net/uid/utils/helpers/RandomHelperTest.java b/src/test/java/ua/net/uid/utils/helpers/RandomHelperTest.java
index 751878c..e370374 100644
--- a/src/test/java/ua/net/uid/utils/helpers/RandomHelperTest.java
+++ b/src/test/java/ua/net/uid/utils/helpers/RandomHelperTest.java
@@ -7,7 +7,7 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-class RandomHelperTest { //TODO RandomHelperTest
+class RandomHelperTest {
 
     RandomHelperTest() {
     }