为什么设置了layout_gravity="right",按钮不会到右边?

Question

下面是Activity.xml文件:
<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" >    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical" >        <ImageView
            android:id="@+id/imageView1"
            android:layout_width="303dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.99"
            android:src="@drawable/ic_launcher" />        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="right"
            android:layout_weight="0.99"
            android:baselineAligned="_baseline"
            android:orientation="horizontal" >            <Button
                android:id="@+id/button1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Button" />            <Button
                android:id="@+id/button2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Button" />            <Button
                android:id="@+id/button3"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="right"
                android:text="Button" />        </LinearLayout>    </LinearLayout></LinearLayout>
为什么设置了layout_gravity="right",button3 不会到右边?    

Answer 1

这是让按钮的内容右对齐，而不是按钮本身