Set your completionThreshold to 1.
<AutoCompleteTextView
android:id="@+id/your_id"
android:layout_width="200dp"
android:layout_height="wrap_content"
android:completionThreshold="1" />
Or to do it dynamically use mAutoCompleteTextView.setThreshold(1)
.
http://developer.android.com/reference/android/widget/AutoCompleteTextView.html