Add this line with your EditText tag.
android:digits="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
Your EditText tag should look like:
<EditText
android:id="@+id/editText1"
android:digits="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…