This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
1. Assuming that you have only a ListView and a button to display in your activity. Say you use LinearLayout; you can set the layout_weight of the ListView to "1" and then have the button below the ListView.
2. If you are using RelativeLayout you can use align_parentBottom property to place the button at the bottom of its parent