title: why the right button can't on the right of parent like left button on the left of parent
body: <pre><code>&lt;LinearLayout
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:orientation="horizontal" &gt;
  
          &lt;Button
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="left"
              android:text="left" /&gt;
  
          &lt;Button
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="center"
              android:text="center" /&gt;
  
          &lt;Button
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="end"
              android:text="right" /&gt;
      &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>I know I can also use Relativelayout and set alignparentRight=true,to let the right button on the right of this parent,But I just want to know,if I use a LinearLayout,how can I make the right button on the right of it's parent? any help thanks</p>