diff --git a/app/src/main/java/ch/ielse/demo/p02/Fragment1.java b/app/src/main/java/ch/ielse/demo/p02/Fragment1.java
index 7f5a025..a876d7f 100644
--- a/app/src/main/java/ch/ielse/demo/p02/Fragment1.java
+++ b/app/src/main/java/ch/ielse/demo/p02/Fragment1.java
@@ -10,10 +10,12 @@
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.app.Fragment;
+import android.text.TextUtils;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.EditText;
 import android.widget.TextView;
 import android.widget.Toast;
 
@@ -37,12 +39,14 @@ public class Fragment1 extends Fragment {
     private ImageWatcherHelper iwHelper;
     private final List<Uri> pictureList = new ArrayList<>();
     private TextView vPictureUris;
+    private EditText vIdx;
 
     @Nullable
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
         View itemView = inflater.inflate(R.layout.fragment, container, false);
 
+        vIdx = itemView.findViewById(R.id.vIdx);
         vPictureUris = itemView.findViewById(R.id.vPictureUris);
         View vAddLocal = itemView.findViewById(R.id.vAddLocal);
 
@@ -58,7 +62,15 @@ public void onClick(View v) {
             @Override
             public void onClick(View v) {
                 if (iwHelper != null) {
-                    iwHelper.show(pictureList);
+                    int currIdx = 0;
+                    try {
+                        if (!TextUtils.isEmpty(vIdx.getText())) {
+                            currIdx = Integer.parseInt(vIdx.getText().toString());
+                        }
+                    } catch (Exception e) {
+                        e.printStackTrace();
+                    }
+                    iwHelper.show(pictureList, currIdx);
                 }
             }
         });
diff --git a/app/src/main/res/layout/fragment.xml b/app/src/main/res/layout/fragment.xml
index 0f61d78..be75d70 100644
--- a/app/src/main/res/layout/fragment.xml
+++ b/app/src/main/res/layout/fragment.xml
@@ -14,8 +14,8 @@
         <TextView
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:textColor="#f00"
-            android:text="这里开始是fragment区域" />
+            android:text="这里开始是fragment区域"
+            android:textColor="#f00" />
 
 
         <Button
@@ -29,6 +29,13 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content" />
 
+        <EditText
+            android:id="@+id/vIdx"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:hint="输入初始化位置，默认0"
+            android:minHeight="20dp" />
+
         <Button
             android:id="@+id/vNoInitPicture"
             android:layout_width="match_parent"
diff --git a/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcher.java b/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcher.java
index bad5237..14e871e 100644
--- a/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcher.java
+++ b/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcher.java
@@ -237,8 +237,15 @@ public interface OnPictureLongPressListener {
         void onPictureLongPress(ImageView v, Uri uri, int pos); // 当前展示图片长按的回调
     }
 
-    public void show(List<Uri> urlList) {
-        show(null, null, urlList);
+    public void show(List<Uri> urlList, int initPos) {
+        if (urlList == null) {
+            throw new NullPointerException("urlList[null]");
+        }
+        if (initPos >= urlList.size() || initPos < 0) {
+            throw new IndexOutOfBoundsException("initPos[" + initPos + "]  urlList.size[" + urlList.size() + "]");
+        }
+        initPosition = initPos;
+        showInternal(null, null, urlList);
     }
 
     /**
@@ -249,12 +256,26 @@ public void show(List<Uri> urlList) {
      * @param urlList        被加载的图片url列表，数量必须大于等于 imageGroupList.size。 且顺序应当和imageGroupList保持一致
      */
     public void show(ImageView i, SparseArray<ImageView> imageGroupList, final List<Uri> urlList) {
+        if (i == null || imageGroupList == null || urlList == null) {
+            throw new NullPointerException("i[" + i + "]  imageGroupList[" + imageGroupList + "]  urlList[" + urlList + "]");
+        }
+        initPosition = -1;
+        for (int x = 0; x < imageGroupList.size(); x++) {
+            if (imageGroupList.get(imageGroupList.keyAt(x)) == i) {
+                initPosition = imageGroupList.keyAt(x);
+                break;
+            }
+        }
+        if (initPosition < 0) {
+            throw new IllegalArgumentException("param ImageView i must be a member of the List <ImageView> imageGroupList!");
+        }
+        showInternal(i, imageGroupList, urlList);
+    }
+
+    private void showInternal(ImageView i, SparseArray<ImageView> imageGroupList, final List<Uri> urlList) {
         if (loader == null) {
             throw new NullPointerException("please invoke `setLoader` first [loader == null]");
         }
-        if ((i == null && imageGroupList != null) || (i != null && imageGroupList == null)) {
-            throw new IllegalArgumentException("666");
-        }
 
         if (i != null && i.getDrawable() == null) return;
 
@@ -265,23 +286,6 @@ public void show(ImageView i, SparseArray<ImageView> imageGroupList, final List<
             return;
         }
 
-        initPosition = -1;
-        if (imageGroupList != null) {
-            for (int x = 0; x < imageGroupList.size(); x++) {
-                if (imageGroupList.get(imageGroupList.keyAt(x)) == i) {
-                    initPosition = imageGroupList.keyAt(x);
-                    break;
-                }
-            }
-        }
-
-        if (initPosition < 0) {
-            if (imageGroupList != null) {
-                throw new IllegalArgumentException("param ImageView i must be a member of the List <ImageView> imageGroupList!");
-            }
-            initPosition = 0;
-        }
-
         currentPosition = initPosition;
 
         if (animImageTransform != null) animImageTransform.cancel();
@@ -1147,7 +1151,7 @@ protected void onSizeChanged(int w, int h, int oldW, int oldH) {
 
     private void internalDisplayDataAfterLayout() {
         if (initUrlList != null) {
-            show(initI, initImageGroupList, initUrlList);
+            showInternal(initI, initImageGroupList, initUrlList);
         }
     }
 
@@ -1205,7 +1209,7 @@ private void animBackgroundTransform(final int colorResult, final int tag) {
         if (colorResult == mBackgroundColor) return;
         if (animBackground != null) animBackground.cancel();
         final int mCurrentBackgroundColor = mBackgroundColor;
-        animBackground = ValueAnimator.ofFloat(0, 1).setDuration(300);
+        animBackground = ValueAnimator.ofFloat(0, 1).setDuration(200);
         animBackground.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
             @Override
             public void onAnimationUpdate(ValueAnimator animation) {
diff --git a/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcherHelper.java b/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcherHelper.java
index ad2961b..fc083e9 100644
--- a/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcherHelper.java
+++ b/imagewatcher/src/main/java/com/github/ielse/imagewatcher/ImageWatcherHelper.java
@@ -71,9 +71,9 @@ public void show(ImageView i, SparseArray<ImageView> imageGroupList, List<Uri> u
         mImageWatcher.show(i, imageGroupList, urlList);
     }
 
-    public void show(List<Uri> urlList) {
+    public void show(List<Uri> urlList, int initPos) {
         init();
-        mImageWatcher.show(urlList);
+        mImageWatcher.show(urlList, initPos);
     }
 
     private void init() {