<?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"   android:paddingBottom="@dimen/activity_vertical_margin"   android:paddingLeft="@dimen/activity_horizontal_margin"   android:paddingRight="@dimen/activity_horizontal_margin"   android:paddingTop="@dimen/activity_vertical_margin"   tools:context="com.example.android.twoactivities.MainActivity">    <Button       android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:text="@string/button_main"       android:id="@+id/button_main"       android:layout_alignParentBottom="true"       android:layout_alignParentRight="true"       android:layout_alignParentEnd="true"       android:onClick="launchSecondActivity"/> </RelativeLayout>