findViewbyID - How to Find a ProgressBar using ID

findViewbyId was added in API Level 1
findViewById: Look for a child ProgressBar with the given id. If this view has a given id, return this ProgressBar. The findViewById() method is available to all activities in Android. findViewById allows you to find a view inside an activity layout.

1. Name a ProgressBar, in XML named myProgressBar.

2. Declare a ProgressBar named myProgressBar.

3. In MainActivity, java file, add the below code to the onCreate method. Where R.id.myProgressBar is the same as the android:id name in your main.xml file, and myProgressBar is the ProgressBar name referred to in Java. This returns a ProgressBar class and is casted to a ProgressBar type so you can work with it.

myProgressBar = (ProgressBar) findViewById(R.id.myProgressBar); 

4. Compile and run!

Resources:

http://developer.android.com/reference/android/view/View.html#findViewById(int)