为什么将layout_gravity设置为left / right在水平LinearLayout中不起作用？

Question

I am trying to have two TextView s one to the left side of the parent and the other to the right.
I was expecting that layout_gravity would be enough to do the trick.
But it doesn't work. Example code:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="300dp"
              android:layout_height="match_parent">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="LEFT"
            android:textSize="14sp"
            android:layout_gravity="left"
            />
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="RIGHT"
            android:textSize="14sp"
            android:layout_gravity="right"
            />
    </LinearLayout>

</LinearLayout>  

What am I doing wrong?

Answer 1

Try this:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="300dp"
  android:layout_height="match_parent">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">
    <TextView
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="LEFT"
        android:layout_weight=".5"
        android:layout_gravity="start"
        android:gravity="start"
        android:textSize="14sp" />
    <TextView
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="RIGHT"
        android:layout_weight=".5"
        android:layout_gravity="end"
        android:gravity="end"
        android:textSize="14sp"/>
</LinearLayout>

Answer 2

LinearLayout doesn't use layout_gravity for the orientation it is laying out. You could use layout_gravity in a horizontal LinearLayout to control how they are place vertically: top, centre or bottom.

You could change your LinearLayout to vertical, then your left/right gravities would work, but the second TextView would be placed further down than the first one. I assume this is not what you want.

It seems to me you are not interested in the layout logic that LinearLayout provides (which is placing it's children one after the other). You want just one to be left aligned and one right aligned. You can use gravity for that effect if you put your TextView s in a FrameLayout instead.

Answer 3

Try this way : Editing Eenvincible's Answer...

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:weightSum="1"
    >
    <TextView
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".5"
        android:text="LEFT"
        android:textSize="14sp"
        android:layout_gravity="left"
        />
    <TextView
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight=".5"
        android:text="RIGHT"
        android:textSize="14sp"
        android:layout_gravity="right"
        />
</LinearLayout>