Can you center a Button in RelativeLayout?

Question

Try

android:layout_centerHorizontal="true"

Exactly like this, it works for me:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="#ff0000">

    <Button
        android:id="@+id/btn_mybutton"
        android:layout_height="wrap_content"
        android:layout_width="124dip"
        android:layout_marginTop="5dip"
        android:layout_centerHorizontal="true"/>

</RelativeLayout>

You can use CENTER_IN_PARENT for relative layout.

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

Arcadia, just try the code below. There are several ways to get the result you're looking for, this is one of the easier ways.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relative_layout"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:gravity="center">

    <Button
        android:id="@+id/the_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Centered Button"/>
</RelativeLayout>

Setting the gravity of the RelativeLayout itself will affect all of the objects placed inside of it. In this case, it's just the button. You can use any of the gravity settings here, of course (e.g. center_horizontal, top, right, and so on).

You could also use this code below:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relative_layout"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent">

    <Button
        android:id="@+id/the_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Centered Button"
        android:layout_centerInParent="true"/>
</RelativeLayout>

Summarized

Adding:

android:layout_centerInParent="true"

just works on RelativeLayout, if one of the following attributes is also set for the view:

android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"

which alignes the child view to the parent view. The "center" is based on the axis of the alignement you have chosen:

left/right -> vertical

top/bottom -> horizontal

Setting the gravity of childs/content inside the view:

android:gravity="center"

is centering the child inside the parent view in any case, if there is no alignment set. Optional you can choose:

<!-- Axis to Center -->
android:gravity="center_horizontal"
android:gravity="center_vertical"

<!-- Alignment to set-->
android:gravity="top"
android:gravity="bottom"
android:gravity="left"
android:gravity="right"
android:gravity="fill"
...

Then there is:

android:layout_gravity="center"

which is centering the view itself inside it's parent

And at last you can add the following attribute to the parents view:

android:layout_centerHorizontal="true"
android:layout_centerVertical="true"

Use the attribute android:centerInParent="true" inside a view , when you want to center the view in Relative layout.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/main_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <TextView
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="NWE"
        android:textSize="30dp"/>
</RelativeLayout>

Its easy, don't align it to anything

<Button
    android:id="@+id/the_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" 
    android:layout_centerInParent="true"
    android:text="Centered Button"/>

To center align in one of the direction use android:layout_centerHorizontal="true" or android:layout_centerVertical="true" in the child layout