How to center a View inside of an Android Layout?

问题:

I want to put a layout in the center of the screen.

回答1:

Step #1: Wrap whatever it is you want centered on the screen in a full-screen RelativeLayout.

Step #2: Give that child view (the one, which you want centered inside the RelativeLayout) the android:layout_centerInParent="true" attribute.

回答2:

You can apply a centering to any View, including a Layout, by using the XML attribute android:layout_gravity". You probably want to give it the value "center".

You can find a reference of possible values for this option here: http://developer.android.com/reference/android/widget/LinearLayout.LayoutParams.html#attr_android:layout_gravity

回答3:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relLayout1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center">
    <ProgressBar
        android:id="@+id/ProgressBar01"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_gravity="center"
        android:layout_height="wrap_content"></ProgressBar>
    <TextView
        android:layout_below="@id/ProgressBar01"
        android:text="@string/please_wait_authenticating"
        android:id="@+id/txtText"
        android:paddingTop="30px"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"></TextView>
</RelativeLayout>

回答4:

I was able to center a view using

android:layout_centerHorizontal="true" 

and

android:layout_centerVertical="true" 

params.

回答5:

If you want to center one view, use this one. In this case TextView must be the lowermost view in your XML because it's layout_height is match_parent.

<TextView 
    android:id="@+id/tv_to_be_centered"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:gravity="center"
    android:text="Some text"
/>

回答6:

Updated answer: Constraint Layout

It seems that the trend in Android now is to use a Constraint layout. Although it is simple enough to center a view using a RelativeLayout (as other answers have shown), the ConstraintLayout is more powerful than the RelativeLayout for more complex layouts. So it is worth learning how do do now.

To center a view, just drag the handles to all four sides of the parent.

回答7:

It will work for that code sometimes need both properties

android:layout_gravity="center"
android:layout_centerHorizontal="true"

回答8:

Add android:layout_centerInParent="true" to element which you want to center in the RelativeLayout

回答9:

Use ConstraintLayout. Here is an example that will center the view according to the width and height of the parent screen:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="#FF00FF"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintHeight_percent=".6"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintWidth_percent=".4"></LinearLayout>
</android.support.constraint.ConstraintLayout>

You might need to change your gradle to get the latest version of ConstraintLayout:

dependencies {
...
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
}