Changes

</RelativeLayout>

</pre>

Also, note that the two child views also have properties declared. In the case of the Button view, it has been assigned ID “button1” and configured to display text that reads “Button”. Additionally, it has been centered vertically and horizontally within the parent view and height and width properties have been declared.

A useful tool for closely inspecting the view hierarchy of an activity is the Hierarchy Viewer. This tool is part of the Android ADT suite and can be launched either from the command-line or within the Eclipse IDE. The main purpose of the tool is to provide a detailed overview of the entire view tree for activities within currently running applications, and to provide information about the performance of each view contained therein.

The hierarchy viewer can only be used to inspect applications that are either running within an Android emulator, or on a device running a development version of Android. To run the tool on the LayoutSample application created in this chapter, launch the application on an Android Virtual Device emulator and wait until it has loaded and is visible on the emulator display. Once running, select the Window -> Open Perspective -> Hierarchy View menu option.

<hr>

<table border="0" cellspacing="0" width="100%">