TestApp

Main_Activity.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:paddingBottom="@dimen/activity_vertical_margin"    app:layout_behavior="@string/appbar_scrolling_view_behavior"    tools:showIn="@layout/activity_main"    tools:context="com.example.bc.myapplication.MainActivity">

    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Hello World"        android:id="@+id/textView"        android:textStyle="bold"        android:textColor="#F00"        android:textSize="30dp"        android:background="#fff"        android:layout_centerVertical="true"        android:layout_centerHorizontal="true" />

</RelativeLayout>