The problem is that you are using a LinearLayout and its children are laid out horizontally by default. Based on the length of the text in your TextView is 'pushing' the Button to the right (horizontally). If you want to change this behavior consider using a different layout or change the orientation of the current LinearLayout by doing so:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
LinearLayout children orientation
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
