content_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".MainActivity"
    tools:showIn="@layout/activity_main">

    <RelativeLayout
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="50dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="16dp"
        android:layout_marginLeft="32dp"
        android:layout_marginRight="16dp"
        android:padding="8dp">

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

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Phone number"
                android:textSize="18sp" />

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:gravity="center_vertical">

                <com.rilixtech.CountryCodePicker
                    android:id="@+id/ccp"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    app:ccp_enableHint="false"
                    app:ccp_defaultCode="91"/>
                <android.support.v7.widget.AppCompatEditText
                    android:layout_marginLeft="5dp"
                    android:id="@+id/phone_number_edt"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:hint="Phone No"
                    android:inputType="phone"/>
            </LinearLayout>
        </LinearLayout>
    </RelativeLayout>

</RelativeLayout>