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page.title=Hello, LinearLayout
parent.title=Hello, Views
parent.link=index.html
@jd:body
<p>A {@link android.widget.LinearLayout} is a GroupView that will lay child View elements
vertically or horizontally.</p>
<ol>
<li>Start a new project/Activity called HelloLinearLayout.</li>
<li>Open the layout file.
Make it like so:
<pre>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1">
<TextView
android:text="red"
android:gravity="center_horizontal"
android:background="#aa0000"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>
<TextView
android:text="green"
android:gravity="center_horizontal"
android:background="#00aa00"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>
<TextView
android:text="blue"
android:gravity="center_horizontal"
android:background="#0000aa"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>
<TextView
android:text="yellow"
android:gravity="center_horizontal"
android:background="#aaaa00"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"/>
</LinearLayout>
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1">
<TextView
android:text="row one"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>
<TextView
android:text="row two"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>
<TextView
android:text="row three"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>
<TextView
android:text="row four"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"/>
</LinearLayout>
</LinearLayout>
</pre>
<p>Carefully inspect the XML. You'll notice how this layout works a lot like
an HTML layout. There is one parent LinearLayout that is defined to lay
its child elements vertically. The first child is another LinearLayout that uses a horizontal layout
and the second uses a vertical layout. Each LinearLayout contains several {@link android.widget.TextView}
elements.</p>
</li>
<li>Now open the HelloLinearLayout Activity and be sure it loads this layout in the <code>onCreate()</code> method:</p>
<pre>
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
</pre>
<p><code>R.layout.main</code> refers to the <code>main.xml</code> layout file.</p>
</li>
<li>Run it.</li>
</ol>
<p>You should see the following:</p>
<img src="images/hello-linearlayout.png" width="150px" />
<p>Notice how the various XML attributes define the View's behavior.
Pay attention to the effect of the <code>layout_weight</code>. Try
experimenting with different values to see how the screen real estate is
distributed based on the weight of each element.</p>
<h3>References</h3>
<ul>
<li>{@link android.widget.LinearLayout}</li>
<li>{@link android.widget.TextView}</li>
</ul>
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