<LinearLayout?xmlns:android="http://schemas.android.com/apk/res/android" ????xmlns:tools="http://schemas.android.com/tools" ????android:layout_width="match_parent" ????android:layout_height="match_parent" ????android:paddingBottom="@dimen/activity_vertical_margin" ????android:paddingLeft="@dimen/activity_horizontal_margin" ????android:paddingRight="@dimen/activity_horizontal_margin" ????android:paddingTop="@dimen/activity_vertical_margin" ????tools:context=".MainActivity"?> ????<EditText? ????????android:id="@+id/et_input" ????????android:layout_width="match_parent" ????????android:layout_height="60dp" android:editable="false"?????? android:background="@drawable/white_bg" android:gravity="right|bottom" ????????/> ? <LinearLayout? ? ????android:layout_width="fill_parent" ???? android:layout_height="wrap_content" ???? android:layout_marginTop="20dp" ? ????android:orientation="horizontal" ???? android:gravity="center_horizontal" ? ????> ? ????<Button? ? ????????android:id="@+id/bt_clear" ? ????????android:layout_width="60dp" ? ????????android:layout_height="60dp" ? ????????android:text="C" ? ????????android:textSize="20sp" ? ????????android:gravity="right|bottom" ? ????????/> ? ?????<Button? ? ????????android:id="@+id/bt_del" ? ????????android:layout_width="60dp" ? ????????android:layout_height="60dp" ? ????????android:text="DEl" ? ????????android:layout_marginLeft="10dp" ? ????????android:textSize="20sp" ? ????????android:gravity="right|bottom" ? ????????/> ??<Button? ? ????????android:id="@+id/bt_divide" ? ????????android:layout_width="60dp" ? ????????android:layout_height="60dp" ? ????????android:text="÷" ? ????????android:layout_marginLeft="10dp" ? ????????android:textSize="20sp" ? ????????android:gravity="right|bottom" ? ????????/> ?<Button? ? ????????android:id="@+id/bt_multiply" ? ????????android:layout_width="60dp" ? ????????android:layout_height="60dp" ? ????????android:text="×" ? ????????android:layout_marginLeft="10dp" ? ????????android:textSize="20sp" ? ????????android:gravity="right|bottom" ? ????????/> ? ???? ? </LinearLayout> </LinearLayout>