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.
res/layout/main.xml 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="fill_parent"
android:layout_height="fill_parent">
<TextView
android:id="@+id/label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Type here:"/>
<EditText
android:id="@+id/entry"
android:layout_width="fill_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.
onCreate() method:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
The setContentView(int) method loads the
layout file for the Activity, specified by the resource
ID — R.layout.main refers to the res/layout/main.xml layout
file.
You should see the following layout: