I know we can set the following values to the android:gravity and android:layout_gravity properties:

center

center_vertical

center_horizontal , etc.

But I am confused regarding both of these.

What is the difference between the usage of android:gravity and android:layout_gravity ?

---

Their names should help you:

android:gravity sets the gravity of the contents (ie it's subviews) of the View it's used on.

android:layout_gravity sets the gravity of the View or Layout relative to its parent.

And an example is here.

---

The difference

android:layout_gravity is the Outside gravity of the View. Specifies the direction in which the View should touch its parent's border.

android:gravity is the Inside gravity of that View. Specifies in which direction its contents should align.

HTML/CSS Equivalents

Android                 | CSS
————————————————————————+————————————
android:layout_gravity  | float
android:gravity         | text-align

Easy trick to help you remember

Take layout-gravity as "Lay-outside-gravity".

---

Inside - Outside

gravity arranges the content inside the view.

lay out _gravity arranges the view's position outside of itself.

Sometimes it helps to see a picture, too. The green and blue are TextViews and the other two background colors are LinearLayouts .

Notes

The layout_gravity does not work for views in a RelativeLayout . Use it for views in a LinearLayout or FrameLayout . See my supplemental answer for more details.

The view's width (or height) has to be greater than its content. Otherwise gravity won't have any effect. Thus, wrap_content and gravity are meaningless together.

The view's width (or height) has to be less than the parent. Otherwise layout_gravity won't have any effect. Thus, match_parent and layout_gravity are meaningless together.

The layout_gravity=center looks the same as layout_gravity=center_horizontal here because they are in a vertical linear layout. You can't center vertically in this case, so layout_gravity=center only centers horizontally.

This answer only dealt with setting gravity and layout_gravity on the views within a layout. To see what happens when you set the gravity of the of the parent layout itself, check out the supplemental answer that I referred to above. (Summary: gravity doesn't work well on a RelativeLayout but can be useful with a LinearLayout .)

So remember, layout _gravity arranges a view in its layout . Gravity arranges the content inside the view.

xml

Here is the xml for the above image for your reference:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="0dp"
        android:layout_weight="1"
        android:background="#e3e2ad"
        android:orientation="vertical" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:textSize="24sp"
            android:text="gravity=" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:background="#bcf5b1"
            android:gravity="left"
            android:text="left" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:background="#aacaff"
            android:gravity="center_horizontal"
            android:text="center_horizontal" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:background="#bcf5b1"
            android:gravity="right"
            android:text="right" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:background="#aacaff"
            android:gravity="center"
            android:text="center" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:background="#d6c6cd"
        android:orientation="vertical" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:textSize="24sp"
            android:text="layout_gravity=" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:layout_gravity="left"
            android:background="#bcf5b1"
            android:text="left" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:layout_gravity="center_horizontal"
            android:background="#aacaff"
            android:text="center_horizontal" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:layout_gravity="right"
            android:background="#bcf5b1"
            android:text="right" />

        <TextView
            android:layout_width="200dp"
            android:layout_height="40dp"
            android:layout_gravity="center"
            android:background="#aacaff"
            android:text="center" />

    </LinearLayout>

</LinearLayout>

Related

Difference between a View's Padding and Margin

Match_parent vs wrap_content

How to set both gravity and layout gravity of a LinearLayout programatically

链接地址: http://www.djcxy.com/p/2720.html

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