how to open custom dialog in activity in android code example

Example: custom dialog in android

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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="250dp"
    android:layout_gravity="center"
    android:layout_marginLeft="55dp"
    android:layout_marginRight="55dp"
    android:gravity="center">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center_vertical"
        android:gravity="center_vertical"
        android:orientation="vertical">

        <android.support.v7.widget.CardView
            android:layout_width="match_parent"
            android:layout_height="165dp"
            android:layout_gravity="center"
            android:layout_marginEnd="60dp"
            android:layout_marginStart="60dp"
            app:cardCornerRadius="8dp"
            app:cardElevation="15dp">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_horizontal"
                android:layout_marginTop="14dp"
                android:gravity="center"
                android:text="Quit Earning?"
                android:textColor="@android:color/black"
                android:textSize="20dp"
                android:textStyle="bold" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginEnd="20dp"
                android:layout_marginStart="20dp"
                android:gravity="center"
                android:text="You are 400pts. away from \n unlocking rewards. quit Earning?"
                android:textSize="18dp"
                android:textStyle="bold" />

        </android.support.v7.widget.CardView>
    </LinearLayout>

    <FrameLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:id="@+id/frmNo"
        android:layout_marginRight="45dp"
        android:layout_marginTop="75dp">

        <android.support.design.widget.FloatingActionButton
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:src="@android:color/transparent"
            app:backgroundTint="@color/fab2" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:elevation="6dp"
            android:text="No"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textColor="@android:color/white"
            android:textStyle="bold" />
    </FrameLayout>

    <FrameLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:id="@+id/frmOk"
        android:layout_marginLeft="50dp"
        android:layout_marginTop="75dp">

        <android.support.design.widget.FloatingActionButton
            android:layout_width="60dp"
            android:layout_height="60dp"
            android:src="@android:color/transparent"
            app:backgroundTint="@color/fab1" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:elevation="6dp"
            android:text="Ok"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textColor="@android:color/white"
            android:textStyle="bold" />
    </FrameLayout>
</FrameLayout>