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Xamarin.Android RelativeLayout

  • Artikkeli

RelativeLayout is a ViewGroup that displays child View elements in relative positions. The position of a View can be specified as relative to sibling elements (such as to the left-of or below a given element) or in positions relative to the RelativeLayout area (such as aligned to the bottom, left of center).

A RelativeLayout is a very powerful utility for designing a user interface because it can eliminate nested ViewGroups. If you find yourself using several nested LinearLayout groups, you may be able to replace them with a single RelativeLayout.

Start a new project named HelloRelativeLayout.

Open the Resources/Layout/Main.axml file and insert the following:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/label"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Type here:"/>
    <EditText
        android:id="@+id/entry"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:drawable/editbox_background"
        android:layout_below="@id/label"/>
    <Button
        android:id="@+id/ok"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/entry"
        android:layout_alignParentRight="true"
        android:layout_marginLeft="10dip"
        android:text="OK" />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toLeftOf="@id/ok"
        android:layout_alignTop="@id/ok"
        android:text="Cancel" />
</RelativeLayout>

Notice each of the android:layout_* attributes, such as layout_below, layout_alignParentRight, and layout_toLeftOf. When using a RelativeLayout, you can use these attributes to describe how you want to position each View. Each one of these attributes define a different kind of relative position. Some attributes use the resource ID of a sibling View to define its own relative position. For example, the last Button is defined to lie to the left-of and aligned-with-the-top-of the View identified by the ID ok (which is the previous Button).

All of the available layout attributes are defined in RelativeLayout.LayoutParams.

Make sure you load this layout in the OnCreate() method:

protected override void OnCreate (Bundle savedInstanceState)
{
    base.OnCreate (savedInstanceState);
    SetContentView (Resource.Layout.Main);
}

The SetContentView(int) method loads the layout file for the Activity, specified by the resource ID — Resource.Layout.Main refers to the Resources/Layout/Main.axml layout file.

Run the application. You should see the following layout:

Screenshot of a relative layout with a TextView, EditText, and two buttons

Resources

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.