Different layout for portraint and landscape

I have the following:

package carcleo.com.cadastro;

import android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;

public class Principal extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Configuration configuration = getResources().getConfiguration();

        if (configuration.orientation == Configuration.ORIENTATION_LANDSCAPE){
            setContentView(R.layout.principal);
        }else{
            setContentView(R.layout.principal(land));
        }

    }
}

In%%, I check the rotation of the screen to display the correct layout .

However, in the folder if , you have 2 files main.xml

The res and principal.xml

That way, I'm not sure how to call the layout when the rotation is LANDSCAPE

LANDSCREEN

LANDcode

<?xmlversion="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"
    android:orientation="horizontal"
    android:background="@drawable/gradient"
    android:padding="16dp"
    tools:context=".Principal">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="249dp"
        android:layout_height="134dp"
        android:layout_alignParentStart="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginStart="0dp"
        android:layout_marginLeft="0dp"
        android:layout_marginTop="0dp"
        android:layout_marginEnd="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginBottom="0dp"
        android:src="@drawable/login" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="200dp"
        android:layout_height="40dp"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true"
        android:layout_marginTop="31dp"
        android:background="#11000000"
        android:drawableLeft="@drawable/ic_action_user"
        android:ems="10"
        android:hint="Usuário"
        android:inputType="textPersonName"
        android:textSize="16dp" />

    <EditText
        android:id="@+id/editText3"
        android:layout_width="200dp"
        android:layout_height="40dp"
        android:layout_alignStart="@+id/editText2"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="165dp"
        android:background="#11000000"
        android:drawableLeft="@drawable/ic_action_senha"
        android:ems="10"
        android:hint="Senha"
        android:inputType="textPassword" />

    <android.support.v7.widget.CardView
        android:layout_width="300dp"
        android:layout_height="50dp"
        android:layout_alignStart="@+id/imageView"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="106dp"
        app:cardBackgroundColor="@color/colorAccent"
        app:cardCornerRadius="25dp"
        app:cardElevation="10dp">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <TextView
                android:id="@+id/textView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:text="Login"
                android:textColor="#FFF"
                android:textSize="18dp" />
        </RelativeLayout>
    </android.support.v7.widget.CardView>

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:layout_marginEnd="414dp"
        android:layout_marginRight="414dp"
        android:layout_marginBottom="45dp"
        android:text="Novo Cadastro" />

</RelativeLayout>

What am I doing wrong if I have already changed

    protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            Configuration configuration = getResources().getConfiguration();

            if (configuration.orientation == 
Configuration.ORIENTATION_LANDSCAPE){
                setContentView(R.layout.principal);
            }else{
                setContentView(R.layout.principal(land));
            }

        }

by

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Configuration configuration = getResources().getConfiguration();

        setContentView(R.layout.principal);

    }

?

On the device and LANDSCAPE the elements are getting one below the other and not on the side as in the design

See AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="carcleo.com.cadastro">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Principal">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".Cadastro" />
        <activity android:name=".Resposta"></activity>
    </application>

</manifest>