Changes

</RelativeLayout>

</pre>

Next, load the ThreadExampleActivity.java file into an editing panel and add code to implement the buttonClick() method which will be called when the Button view is touched by the user. Since the goal here is to demonstrate the problem of performing lengthy tasks on the main thread, the code will simply pause for 20 seconds before displaying different text on the TextView object:

A close inspection of the updated code for the buttonClick() method will reveal that the code to update the TextView has been removed. As previously stated, updating a user interface element from within a thread other than the main thread violates a key rule of Android development. In order to update the user interface, therefore, it will be necessary to implement a Handler for the thread.

== Implementing a Thread Handler ==

Compile and run the application and, once executing, touch the button. After a 20 second delay, the new text will appear in the TextView object in the user interface.

== Passing a Message to the Handler ==