diff --git a/src/main/java/com/reandroid/utils/NumbersUtil.java b/src/main/java/com/reandroid/utils/NumbersUtil.java
new file mode 100644
index 000000000..0d6ef66a3
--- /dev/null
+++ b/src/main/java/com/reandroid/utils/NumbersUtil.java
@@ -0,0 +1,32 @@
+/*
+ *  Copyright (C) 2022 github.com/REAndroid
+ *
+ *  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 com.reandroid.utils;
+
+public class NumbersUtil {
+
+    public static int abs(int i){
+        if(i < 0){
+            i = -i;
+        }
+        return i;
+    }
+    public static int min(int i1, int i2){
+        if(i1 < i2){
+            return i1;
+        }
+        return i2;
+    }
+}
diff --git a/src/main/java/com/reandroid/utils/StringsUtil.java b/src/main/java/com/reandroid/utils/StringsUtil.java
index 0ded987ca..f0ebe5b19 100644
--- a/src/main/java/com/reandroid/utils/StringsUtil.java
+++ b/src/main/java/com/reandroid/utils/StringsUtil.java
@@ -15,6 +15,8 @@
  */
 package com.reandroid.utils;
 
+import com.reandroid.utils.collection.ArrayIterator;
+
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.List;
@@ -540,5 +542,39 @@ public static int compareStrings(String s1, String s2) {
         return CompareUtil.compare(s1, s2);
     }
 
+    public static String join(Iterable<?> iterable, Object separator){
+        return join(iterable.iterator(), separator);
+    }
+    public static String join(Object[] items, Object separator){
+        return join(ArrayIterator.of(items), separator);
+    }
+    public static String join(Iterator<?> iterator, Object separator){
+        StringBuilder builder = new StringBuilder();
+        boolean appendOnce = false;
+        while (iterator.hasNext()){
+            if(appendOnce){
+                builder.append(separator);
+            }
+            builder.append(iterator.next());
+            appendOnce = true;
+        }
+        if(appendOnce){
+            return builder.toString();
+        }
+        return EMPTY;
+    }
+    public static int diffStart(String str1, String str2){
+        if(isEmpty(str1) || isEmpty(str2) || str1.equals(str2)){
+            return -1;
+        }
+        int length = NumbersUtil.min(str1.length(), str2.length());
+        for(int i = 0; i < length; i++){
+            if(str1.charAt(i) != str2.charAt(i)){
+                return i;
+            }
+        }
+        return -1;
+    }
+
     private static final int MAX_STRING_APPEND = 5;
 }