diff --git a/lib_base/src/main/java/com/android/base/adapter/recycler/ItemViewBinder.kt b/lib_base/src/main/java/com/android/base/adapter/recycler/ItemViewBinder.kt
index 3b85ca3..d67b5b1 100644
--- a/lib_base/src/main/java/com/android/base/adapter/recycler/ItemViewBinder.kt
+++ b/lib_base/src/main/java/com/android/base/adapter/recycler/ItemViewBinder.kt
@@ -26,9 +26,13 @@ abstract class SimpleItemViewBinder<T> : ItemViewBinder<T, KtViewHolder>() {
             inflater.inflate(layout, parent, false)
         } else
             layout as View
-        return KtViewHolder(itemView)
+        return KtViewHolder(itemView).apply {
+            onViewHolderCreated(this)
+        }
     }
 
+    protected open fun onViewHolderCreated(viewHolder: KtViewHolder) = Unit
+
     /**provide a layout id or a View*/
     abstract fun provideLayout(inflater: LayoutInflater, parent: ViewGroup): Any
 
diff --git a/lib_base/src/main/java/com/android/base/kotlin/Collections.kt b/lib_base/src/main/java/com/android/base/kotlin/Collections.kt
new file mode 100644
index 0000000..8f33905
--- /dev/null
+++ b/lib_base/src/main/java/com/android/base/kotlin/Collections.kt
@@ -0,0 +1,7 @@
+package com.android.base.kotlin
+
+import com.android.base.utils.common.CollectionUtils
+
+fun <T> List<T>?.toArrayList(): ArrayList<T> {
+    return CollectionUtils.toArrayList(this)
+}
\ No newline at end of file
diff --git a/lib_base/src/main/java/com/android/base/kotlin/SizeEx.kt b/lib_base/src/main/java/com/android/base/kotlin/SizeEx.kt
index b99dc04..a555455 100644
--- a/lib_base/src/main/java/com/android/base/kotlin/SizeEx.kt
+++ b/lib_base/src/main/java/com/android/base/kotlin/SizeEx.kt
@@ -1,27 +1,8 @@
 package com.android.base.kotlin
 
-import android.content.Context
-import android.support.v4.app.Fragment
-import android.support.v7.widget.RecyclerView
-import android.view.View
 import com.android.base.utils.android.UnitConverter
 
-fun Context.dip(value: Int): Int = UnitConverter.dpToPx(value)
-fun Context.dip(value: Float): Float = UnitConverter.dpToPx(value)
-fun Context.sp(value: Int): Int = UnitConverter.spToPx(value)
-fun Context.sp(value: Float): Float = UnitConverter.spToPx(value)
-
-fun Fragment.dip(value: Int): Int = UnitConverter.dpToPx(value)
-fun Fragment.dip(value: Float): Float = UnitConverter.dpToPx(value)
-fun Fragment.sp(value: Int): Int = UnitConverter.spToPx(value)
-fun Fragment.sp(value: Float): Float = UnitConverter.spToPx(value)
-
-fun View.dip(value: Int): Int = context.dip(value)
-fun View.dip(value: Float): Float = context.dip(value)
-fun View.sp(value: Int): Int = context.sp(value)
-fun View.sp(value: Float): Float = context.sp(value)
-
-fun RecyclerView.ViewHolder.dip(value: Int): Int = itemView.dip(value)
-fun RecyclerView.ViewHolder.dip(value: Float): Float = itemView.dip(value)
-fun RecyclerView.ViewHolder.sp(value: Int): Int = itemView.dip(value)
-fun RecyclerView.ViewHolder.sp(value: Float): Float = itemView.dip(value)
\ No newline at end of file
+fun dip(value: Int): Int = UnitConverter.dpToPx(value)
+fun dip(value: Float): Float = UnitConverter.dpToPx(value)
+fun sp(value: Int): Int = UnitConverter.spToPx(value)
+fun sp(value: Float): Float = UnitConverter.spToPx(value)
\ No newline at end of file
diff --git a/lib_base/src/main/java/com/android/base/utils/common/CollectionUtils.java b/lib_base/src/main/java/com/android/base/utils/common/CollectionUtils.java
index 1332c74..e285ca4 100644
--- a/lib_base/src/main/java/com/android/base/utils/common/CollectionUtils.java
+++ b/lib_base/src/main/java/com/android/base/utils/common/CollectionUtils.java
@@ -1,7 +1,6 @@
 package com.android.base.utils.common;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 
@@ -21,11 +20,4 @@ public class CollectionUtils {
         return new ArrayList<>(list);
     }
 
-    public static <T> List<T> emptyIfNull(List<T> list) {
-        if (list == null) {
-            return Collections.emptyList();
-        }
-        return list;
-    }
-
 }