Activity and Layout xml
Last post we looked at AndroidManifest.xml here. We talked about activities and an entry point to it. Here we will look at that activity.
<activity android:name=".SendActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Here,
SendActivity is the
MAIN activity. A
SendActivity.java must be created in the
"src" directory of your code. Note that the file name and the activity name should match. A code snippet of it looks like this:
public class SendActivity extends Activity {
/* variables can be defined here */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
Here we see that
SendActivity is a class that inherits from the
Activity. We also see that there is the
onCreate function which is the entry function for the
SendActivity class. Inside it, the view for application is mentioned:
setContentView(R.layout.main);
So the screen will display the contents of the
main.xml file which will be found under the
layout folder in the
res folder.
The
main.xml file looks like:
<?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="wrap_content">
<EditText
android:id="@+id/msgTextField"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1.0"
android:hint="Enter Message"
/>
<Button
android:text="Send"
android:id="@+id/sendButton"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:onClick="send"
android:lines="1"
/>
</LinearLayout>
<WebView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/webView"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1.0"
/>
</LinearLayout>
Your app can have a
LinearLayout or a
RelativeLayout on which suits you. Here the screen will display an
EditText field for the user to input data, a Send
Button and a
WebView below it. A
WebView is used to display a webpage within the app. A screenshot on the emulator looks like this.
Here ends the short tutorial for beginners!
