android:nextFocusDown
You have to be careful about setting android:nextFocusDown in your XML layout because errors will be thrown if the objects you are referencing haven't been created yet. I ran into that situation, so I set the references programmatically.
In this instance, I have three side-by-side-by-side EditText objects inside of a RelativeLayout: et1, et2 and et3. Pressing the next button in et1 should focus et2. Pressing the next button in et2 should focus et3. Finally, a "Done" button is in place for et3 so we can stop there. The code to accomplish this is listed below:
// Get references to layout objects
EditText et1=(EditText)findViewById(R.id.et1);
EditText et2=(EditText)findViewById(R.id.et2);
EditText et3=(EditText)findViewById(R.id.et3);
// Set keyboard next buttons
et1.setNextFocusDownId(R.id.et2);
et2.setNextFocusDownId(R.id.et3);