How to center items of a recyclerview?

Achieved with:

recyclerView.adapter = MyAdapter()
val layoutManager = FlexboxLayoutManager(context).apply {
    justifyContent = JustifyContent.CENTER
    alignItems = AlignItems.CENTER
    flexDirection = FlexDirection.ROW 
    flexWrap = FlexWrap.WRAP
}
recyclerView.layoutManager = layoutManager

You need to add FlexboxLayout to your gradle:

implementation 'com.google.android.flexbox:flexbox:3.0.0'

Make recyclerview width to wrap_content and its container's layout_gravity to center_horizontal

 <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="vertical">

      <android.support.v7.widget.RecyclerView
           android:id="@+id/recycrer_view"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_gravity="center_horizontal"
           android:paddingLeft="16dp"
           android:paddingRight="16dp" />
 </LinearLayout>

Take LinearLayout in your RecyclerView's item row layout then give android:layout_gravity="center" to LinearLayout.

For each row of images you have to take different LinearLayout.

Here is example code:

 <LinearLayout
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
         android:orientation="horizontal">

            <ImageView
                android:id="@+id/image1"
                android:layout_width="64dp"
                android:layout_height="64dp"
                android:layout_marginRight="10dp"
                android:layout_weight="1"
                android:src="@drawable/image1" />

            <ImageView
                android:id="@+id/image2"
                android:layout_width="64dp"
                android:layout_height="64dp"
                android:layout_marginLeft="10dp"
                android:layout_marginRight="10dp"
                android:layout_weight="1"
                android:src="@drawable/image2" />

           <ImageView
                android:id="@+id/image3"
                android:layout_width="64dp"
                android:layout_height="64dp"
                android:layout_marginLeft="10dp"
                android:layout_marginRight="10dp"
                android:layout_weight="1"
                android:src="@drawable/image3" />

  </LinearLayout>

I am assuming that you are using a LinearLayoutManager with a RecyclerView for a ListView-style effect. In that case, use a horizontal LinearLayout for each row, with android:gravity="center" to center its contents.