Fix: Notify Adapter Changed

app/src/main/java/com/jackandphantom/carousellayout/MainActivity.kt

@@ -22,17 +22,19 @@ class MainActivity : AppCompatActivity() {
         list.add(DataModel(R.drawable.hobes, "Thi is cool"))
         list.add(DataModel(R.drawable.guypro, "Thi is cool"))
         list.add(DataModel(R.drawable.joker, "Thi is cool"))
-        list.add(DataModel(R.drawable.londonlove, "Thi is cool"))
+       // list.add(DataModel(R.drawable.londonlove, "Thi is cool"))
 
         val adapter = DataAdapter(list)
 
         binding.recycler.apply {
             this.adapter = adapter
             set3DItem(true)
             setAlpha(true)
-            setInfinite(true)
         }
-        val carouselLayoutManager = binding.recycler.getCarouselLayoutManager()
-       // carouselLayoutManager.scrollToPosition(4)
+
+        //Trigger the button and put your useCase to test different cases of adapter
+        binding.button.setOnClickListener {
+            adapter.removeData()
+        }
     }
 }

app/src/main/java/com/jackandphantom/carousellayout/adapter/DataAdapter.kt

@@ -9,7 +9,7 @@ import com.bumptech.glide.Glide
 import com.example.customviewimple.model.DataModel
 import com.jackandphantom.carousellayout.R
 
-class DataAdapter (private var list : List<DataModel>): RecyclerView.Adapter<DataAdapter.ViewHolder>() {
+class DataAdapter (private var list : ArrayList<DataModel>): RecyclerView.Adapter<DataAdapter.ViewHolder>() {
 
      class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
          val image : ImageView = itemView.findViewById(R.id.image)
@@ -28,8 +28,24 @@ class DataAdapter (private var list : List<DataModel>): RecyclerView.Adapter<Dat
         Glide.with(holder.image).load(list.get(position).img).into(holder.image)
     }
 
-    fun updateData(list: List<DataModel>) {
+    fun updateData(list: ArrayList<DataModel>) {
         this.list = list
         notifyDataSetChanged()
     }
+
+    //Use the method for item changed
+    fun itemChanged() {
+        // remove last item for test purposes
+        this.list[0] = (DataModel(R.drawable.londonlove, "Thi is cool"))
+        notifyItemChanged(0)
+
+    }
+
+    //Use the method for checking the itemRemoved
+    fun removeData() {
+        // remove last item for test purposes
+        val orgListSize = list.size
+        this.list = this.list.subList(0, orgListSize - 1).toList() as ArrayList<DataModel>
+        notifyItemRemoved(orgListSize - 1)
+    }
 }

app/src/main/res/layout/activity_main.xml

@@ -1,14 +1,23 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:orientation="vertical"
     tools:context=".MainActivity">
 
     <com.jackandphantom.carouselrecyclerview.CarouselRecyclerview
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
+        android:layout_gravity="center"
         android:id="@+id/recycler"/>
 
-</FrameLayout>
+    <Button
+        android:id="@+id/button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="50dp"
+        android:text="@string/removeitem" />
+
+</LinearLayout>

app/src/main/res/values/strings.xml

@@ -1,3 +1,4 @@
 <resources>
     <string name="app_name">CarouselLayout</string>
+    <string name="removeitem">removeItem</string>
 </resources>

carouselrecyclerview/src/main/java/com/jackandphantom/carouselrecyclerview/CarouselLayoutManager.kt

@@ -464,8 +464,9 @@ class CarouselLayoutManager constructor(
      * It's also used in the [CarouselRecyclerview.getChildDrawingOrder] for measure the order of the child
      */
     fun getChildActualPos(index: Int): Int {
-        val child = getChildAt(index)
-        if (child!!.tag != null) {
+        val child = getChildAt(index) ?: return Int.MIN_VALUE
+
+        if (child.tag != null) {
             val tag = checkTAG(child.tag)
             if (tag != null)
             return tag.pos

carouselrecyclerview/src/main/java/com/jackandphantom/carouselrecyclerview/CarouselRecyclerview.kt

@@ -84,7 +84,7 @@ class CarouselRecyclerview(context: Context, attributeSet: AttributeSet) : Recyc
 
     /**
      * Get the layout manager instance
-     * @return CoverLayout
+     * @return carouselLayoutManager
      */
      fun getCarouselLayoutManager(): CarouselLayoutManager {
         return layoutManager as CarouselLayoutManager
@@ -100,32 +100,31 @@ class CarouselRecyclerview(context: Context, attributeSet: AttributeSet) : Recyc
     override fun getChildDrawingOrder(childCount: Int, i: Int): Int {
         val center: Int = getCarouselLayoutManager().centerPosition()
 
-        // Get the actual position of the i-th child view in RecyclerView
-
         // Get the actual position of the i-th child view in RecyclerView
         val actualPos: Int = getCarouselLayoutManager().getChildActualPos(i)
-
-        // The number of intervals from the middle item
-
-        // The number of intervals from the middle item
-        val dist = actualPos - center
-
-        var order: Int
-        // [< 0] indicates that the item is located to the left of the middle item and can be drawn in order
-        // [< 0] indicates that the item is located to the left of the middle item and can be drawn in order
-        order = if (dist < 0) {
-            i
-        } else {
-            //[>= 0] It means that the item is located to the right
-            // of the middle item, and the order needs to be reversed.
-            childCount - 1 - dist
+        var order: Int = i
+
+        if (actualPos != Int.MIN_VALUE) {
+
+            // The number of intervals from the middle item
+            val dist = actualPos - center
+            // [< 0] indicates that the item is located to the left of the middle item and can be drawn in order
+            // [< 0] indicates that the item is located to the left of the middle item and can be drawn in order
+            order = if (dist < 0) {
+                i
+            } else {
+                //[>= 0] It means that the item is located to the right
+                // of the middle item, and the order needs to be reversed.
+                childCount - 1 - dist
+            }
         }
 
         if (order < 0) order = 0 else if (order > childCount - 1) order = childCount - 1
 
         return order
     }
 
+
     fun setItemSelectListener(listener: CarouselLayoutManager.OnSelected) {
         getCarouselLayoutManager().setOnSelectedListener(listener)
     }
@@ -163,7 +162,5 @@ class CarouselRecyclerview(context: Context, attributeSet: AttributeSet) : Recyc
     override fun setAdapter(adapter: Adapter<*>?) {
         super.setAdapter(adapter)
         restorePosition()
-
     }
-
 }