Java android布局，带有两个RelativeLayout的按钮

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <RelativeLayout
        android:id="@+id/relativeLayout1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <!-- 在这里添加第一个按钮的代码 -->

    </RelativeLayout>

    <RelativeLayout
        android:id="@+id/relativeLayout2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/relativeLayout1">

        <!-- 在这里添加第二个按钮的代码 -->

    </RelativeLayout>

</RelativeLayout>