How to align LinearLayout at the center of its parent?

问题

I've looked through numerous similar questions here at SO, but nothing helps. I have a hierarchy of different nested layouts, all have android:layout_width="fill_parent", and the inner-most layout has android:layout_width="wrap_content - I need to align it at the center (horizontally). How do I do that?

Update:: I've found the cause of the problem - if I put the inner LinearLayout into RelativeLayout with android:layout_width="fill_parent", it still wraps it's content. The TableRow, however, is really filling the screen.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
        <TableLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" >
            <TableRow >
            <LinearLayout 
            android:orientation="horizontal"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content">
                    <TextView
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"
                    android:text="1"
                    android:textAppearance="?android:attr/textAppearanceLarge" />

                     <TextView
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"
                    android:text="2"
                    android:textAppearance="?android:attr/textAppearanceLarge" />
             </LinearLayout>
           </TableRow>
        </TableLayout>
    </FrameLayout>
</LinearLayout>

回答1:

These two attributes are commonly confused:

android:gravity sets the gravity of the content of the View it's used on.
android:layout_gravity sets the gravity of the View or Layout relative to its parent.

So either put android:gravity="center" on the parent or android:layout_gravity="center" on the LinearLayout itself.

I have caught myself a number of times mixing them up and wondering why things weren't centering properly...

回答2:

Please try this in your linear layout

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

回答3:

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    >
    <LinearLayout 
            android:orientation="horizontal"
            android:layout_centerHorizontal="true"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">
            <TextView
                 android:layout_height="wrap_content"
                 android:layout_width="wrap_content"
                 android:text="1"
                 android:textAppearance="?android:attr/textAppearanceLarge" />

           <TextView
                 android:layout_height="wrap_content"
                 android:layout_width="wrap_content"
                 android:text="2"
                 android:textAppearance="?android:attr/textAppearanceLarge" />
    </LinearLayout>
</RelativeLayout>

consider wrapping relativeLayout over LinearLayout. android:layout_centerHorizontal="true" will position the view center horizontal.

回答4:

add layout_gravity="center" or "center_horizontal" to the parent layout.

On a side note, your LinearLayout inside your TableRow seems un-necessary, as a TableRow is already an horizontal LinearLayout.

回答5:

Try this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    >
    <FrameLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
        <TableLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" >
            <TableRow >
            <LinearLayout 
            android:orientation="horizontal"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:gravity="center_horizontal" 
                    android:layout_gravity="center_horizontal" >
                    <TextView
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"
                    android:text="1"
                    android:textAppearance="?android:attr/textAppearanceLarge" />

                     <TextView
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"
                    android:text="2"
                    android:textAppearance="?android:attr/textAppearanceLarge" />
             </LinearLayout>
           </TableRow>
        </TableLayout>
    </FrameLayout>
</LinearLayout>

回答6:

This worked for me.. adding empty view ..

<LinearLayout
       android:layout_width="match_parent"
        android:layout_height="wrap_content"
       android:layout_gravity="center_horizontal"
        android:orientation="horizontal"
         >
<View
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_weight="1"
            />  
     <com.google.android.gms.ads.AdView

         android:id="@+id/adView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"

         android:layout_gravity="center_horizontal"
         ads:adSize="BANNER"
         ads:adUnitId="@string/banner_ad_unit_id" >

    </com.google.android.gms.ads.AdView>
    <View
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_weight="1"
            />  
    </LinearLayout>

回答7:

Try <TableRow android:gravity="center_horizontal"> This will center the inner LinearLayout within the tablerow.

回答8:

I have faced the same situation while designing custom notification. I have tried with the following attribute set with true.

 android:layout_centerInParent.

回答9:

@jksschneider explation is almost right. Make sure that you haven't set any gravity to parent layout, and then set layout_gravity="center" to your view or layout.

回答10:

this worked for me.

<LinearLayout>
.
.
.
android:gravity="center"
.
.>

<TextView
android:layout_gravity = "center"
/>
<Button
android:layout_gravity="center"
/>

</LinearLayout>

so you're designing the Linear Layout to place all its contents(TextView and Button) in its center and then the TextView and Button are placed relative to the center of the Linear Layout

回答11:

I experienced this while working with nested RelativeLayouts. My solution ended up being simple, but it's a little gotcha that's worth being aware of.

My layout was defined with...

android:layout_height="fill_parent"
android:layout_below="@id/someLayout
android:gravity="center"

...however, I didn't think that the layout below this one was placed on top of it. Everything inside this layout was shifted towards the bottom instead of centered. Adding...

android:layout_above="@id/bottomLayout"

...fixed my issue.

回答12:

for ImageView or others views who layout-gravity or gravity does not exist use : android:layout_centerInParent="true" in the child (I had a relative layout with an ImageView as a child).

回答13:

The problem is that the root's (the main layout you store the other elements) gravity is not set. If you change it to center the other elements' gravity must work just fine.

回答14:

Below is code to put your Linearlayout at bottom and put its content at center. You have to use RelativeLayout to set Layout at bottom.

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

  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:background="#97611F"
    android:gravity="center_horizontal"
    android:layout_alignParentBottom="true"
    android:orientation="horizontal">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text="View Saved Searches"
        android:textSize="15dp"
        android:textColor="#fff"
        android:gravity="center_vertical"
        android:visibility="visible" />
    <TextView
        android:layout_width="30dp"
        android:layout_height="24dp"
        android:text="12"
        android:textSize="12dp"
        android:textColor="#fff"
        android:gravity="center_horizontal"
        android:padding="1dp"
        android:visibility="visible" />
  </LinearLayout>  
</RelativeLayout>

来源：https://stackoverflow.com/questions/8180887/how-to-align-linearlayout-at-the-center-of-its-parent

标签

android

android-layout

android-ui