In the below example I have created a dialog button layout. Here I have created a main.activity layout, In main.xml layout first I have created  Relative layout and added all layout in this Main Relative layout then I have  created a Relative layout for body of paticular size of dilog box and I have also added TextView, ImageView, ImageButton. In below second step I have creted rounded.xml layout in drawable folder here I have added dialog shape and color properties. You can see below program it will clearly describe you to create dialog with cross button layout.

Step(1)-main_activity.xml layout-

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="300dp"
    android:layout_height="wrap_content">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginTop="15dp"
        android:background="@drawable/rounded_border">

        <!--Main Body of your custom dialog-->

        <RelativeLayout
            android:layout_width="match_parent"
            android:id="@+id/editbusineslayout"
            android:layout_height="50dp">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="80dp"
                android:gravity="center"
                android:text="@string/edit_business"
                android:textColor="@color/colorPrimary"
                android:textSize="@dimen/text_large"
                android:textStyle="bold"/>
        </RelativeLayout>

        <ImageView
            android:id="@+id/lineimageview"
            android:layout_below="@+id/editbusineslayout"
            android:layout_width="match_parent"
            android:layout_height="0.8dp"
            android:src="@color/colorPrimary"/>
        <RelativeLayout
            android:layout_below="@+id/lineimageview"
            android:layout_width="match_parent"
            android:id="@+id/editOfferslayout"
            android:layout_height="50dp">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="80dp"
                android:gravity="center"
                android:text="@string/edit_offers"
                android:textColor="@color/colorPrimary"
                android:textSize="@dimen/text_large"
                android:textStyle="bold"/>
        </RelativeLayout>
    </RelativeLayout>

    <LinearLayout
        android:id="@+id/llTop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"

        android:layout_alignParentTop="true"
        android:orientation="vertical">

        <ImageButton
            android:id="@+id/btnCancel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/btnBookK"
            android:background="@null"
            android:src="@mipmap/ic_close_circle_outline_black_36dp" />

    </LinearLayout>

</RelativeLayout>


Step(2)-Create a rounded.xml layout in drawable folder 
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <item>
        <shape android:shape="rectangle" >
            <solid android:color="@color/font_color" />
            <corners android:radius="12dip" />
            <stroke
                android:width="1dip"
                android:color="@color/colorPrimaryDark" />
        </shape>
    </item>
</layer-list>