android:layout_alignTop does not work similar to android:layout_alignBottom

Question

I try to create a semi-transparent red View and a TextView inside RelativeLayout, which the height of View follows the height of TextView, it works as expected when the TextView is above the semi-transparent red View:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<View
    android:background="#FF0000"
    android:alpha="0.5"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@id/textView"/>
<TextView
    android:id="@+id/textView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="TEST"
    android:textSize="50dp"
    android:textColor="#000000"/>
</RelativeLayout>

but I want to change it a bit: put the View above the TextView and others remain unchanged, I tried change android:layout_alignBottom into android:layout_alignTop:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<View
    android:background="#FF0000"
    android:alpha="0.5"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignTop="@id/textView"/>
<TextView
    android:id="@+id/textView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="TEST"
    android:textSize="50dp"
    android:textColor="#000000"/>
</RelativeLayout>

but now the View seems doesn't follow the height of TextView:

What is the problem and how can I fix it?

I think it's not possible to be done by only xml. If you need to put you `View` above the `TextView`, it cannot achieve the alignment of their height. — BakaWaii, Jul 27 '17 at 07:49

score 1 · Accepted Answer · answered Jul 27 '17 at 07:45

Add android:layout_alignBottom="@+id/textView" in View. e.g.-

<View
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignTop="@id/textView"
        android:layout_alignBottom="@+id/textView"
        android:alpha="0.5"
        android:background="#FF0000" />

score 0 · Answer 2 · answered Jul 27 '17 at 08:19

I want to change it a bit: put the View above the TextView and others remain unchanged

If by saying above you mean atop of TextView regarding z-axis, then you're in a wrong way.

What you can do, is just to change the ordering of the views in your layout: the layout that is declared the first will be laid out first, next one would be laid out atop of it.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TEST"
        android:textSize="50dp"
        android:textColor="#000000"/>

    <View
        android:background="#FF0000"
        android:alpha="0.5"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/textView"/>
</RelativeLayout>

android:layout_alignTop does not work similar to android:layout_alignBottom

2 Answers2