Alternative main Activity

Let's take a little break from Services and cover an easier topic...

In this tutorial I will explain how you can create an alternative main Activity using the attribute android:enabled in the AndroidManifest.xml file.

An alternative main Activity could be useful for different purposes: a brief description or tutorial covering the main features of your app, or for a setup process for example. Of course, you want the alternative main Activity to be started only once (the first time the user launches the app), while afterwards the regular main Activity should be used.

To begin with, we declare the two Activities in the AndroidManifest.xml file, like in the following example:

<activity

   android:name=”.ActivityTutorial”

   android:label=”@string/activity_tutorial_label”

   android:icon=”@drawable/activity_tutorial_icon”

   android:enabled=”true”>

   <intent-filter>

      <action android:name=”android.intent.action.MAIN”/>

      <category android:name=”android.intent.category.LAUNCHER”/>

   </intent-filter>

</activity>

<activity

   android:name=”.ActivityMain”

   android:label=”@string/activity_main_label”

   android:icon=”@drawable/activity_main_icon”

   android:enabled=”false”>

   <intent-filter>

      <action android:name=”android.intent.action.MAIN”/>

      <category android:name=”android.intent.category.LAUNCHER”/>

   </intent-filter>

</activity>

There are two things to notice in the previous example: the enabled attribute is set to true for the tutorial Activity (this is the Activity that starts when the user launches the app for the first time) and false for the usual main Activity.

Notice also the intent filter of the two Activities: it is the same because both Activities are used as the main Activity of your app: the ActivityTutorial only the first time, the ActivityMain from the second time onwards.

In order to toggle the enabled attribute of the two Activities (from true to false for ActivityTutorial, from false to true for ActivityMain) we use the following code within the ActivityTutorial:

PackageManager myPackageManager = getPackageManager();

//let’s disable the ActivityTutorial

myPackageManager.setComponentEnabledSetting(new ComponentName(this, ActivityTutorial.class), PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);

//let’s enable the ActivityMain

myPackageManager.setComponentEnabledSetting(new ComponentName(this, ActivityMain.class), PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);

We used the DONT_KILL_APP flag because we don’t want to kill the app containing the component.

The class PackageManager belongs to the following package: android.content.pm.