Vertically centering a view in Android

Question

I'm trying to center a View vertically on screen with the following layout:

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     android:orientation="vertical"     android:layout_width="fill_parent"     android:layout_height="fill_parent" >     <EditText          android:text="example text"           android:layout_width="wrap_content"          android:layout_height="wrap_content"         android:layout_gravity="center_vertical" /> </LinearLayout> 

However it doesn't work. The EditText is still at the top of the screen. Can someone explain what I'm doing wrong here?

NOTE: if I add center_horizontal to the layout_gravity attribute then it centers it horizontally, but still does not center vertically.

UPDATE: using android:gravity="center_vertical" on the parent worked. I still don't understand why android:layout_gravity="center_vertical" on the child didn't work.

Answer 1

I track the answer on Google groups, here it is © Romain Guy:

Well, first of all RelativeLayout ignores layout_gravity. Then you need to know that gravity means "apply gravity to the content of this view" whereas layout_gravity means "apply gravity to this view within its parent." So on a TextView, gravity will align the text within the bounds of the TextView whereas layout_gravity will align the TextView within the bounds of its parent.

Answer 2

There are three ways you can center a view vertically. I recommend using the ConstraintLayout now.

1. Horizontal LinearLayout

The key is orientation="horizontal". You can't center horizontally for orientation="vertical".

<LinearLayout     xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="horizontal">      <EditText         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_gravity="center_vertical"         android:text="example text"/>  </LinearLayout> 

2. RelativeLayout

With a RelativeLayout you can use layout_centerVertical="true".

<RelativeLayout     xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent">      <EditText         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_centerVertical="true"         android:text="example text"/>  </RelativeLayout>  

3. ConstraintLayout

It is easiest to show you this one.

Here is the XML. It still would need a horizontal constraint to be added.

<android.support.constraint.ConstraintLayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context="com.example.constraintlayout.MainActivity"     tools:layout_editor_absoluteX="0dp"     tools:layout_editor_absoluteY="81dp">      <EditText         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginBottom="8dp"         android:layout_marginTop="8dp"         android:text="example text"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintTop_toTopOf="parent"         tools:layout_editor_absoluteX="16dp"/>  </android.support.constraint.ConstraintLayout>