Two launcher activities on phone, one on tablet

Question

I am creating an application for Android 4.0+, and I want to achieve this behavior. Two different activities will have two launcher icons when the user's device is a phone, and it will be just one (the activities will consist of fragments that I will display as tabs in one main activity) on tablet devices. I know that one can set up multiple launcher activities in the manifest, but I think that maybe I would need something that will determine this operation during runtime (in java code).

Answer 1

Two different activities will have two launcher icons when the user's device is a phone, and it will be just one (the activities will consist of fragments that I will display as tabs in one main activity) on tablet devices.

There is no concept in Android of "phone" and "tablet". I am going to assume that you are distinguishing between "phone" and "tablet" in terms of screen size.

If that is true:

Step #1: Create a res/values/bools.xml file and define two <bool> resources, is_phone and is_tablet. Have is_phone be true and is_tablet be false.

Step #2: Create a res/values-.../bools.xml file, where ... is whatever qualifier you are using with your layouts to distinguish between "phones" and "tablets" (e.g., -large, -xlarge, -swNNNdp). Define the same two <bool> resources there with opposite values (i.e., is_phone is false, is_tablet is true).

Step #3: Add both activities to your manifest, each set up for the MAIN/LAUNCHER <intent-filter>. On the one you want to use on a "phone", add android:enabled="@bool/is_phone" to the <activity> element. On the one you want to use on a "tablet", add android:enabled="@bool/is_tablet" to the <activity> element.

This way, based on the same rules that you are using for your layouts, you will have a different launcher activity.

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Apparently, this doesn't work, though I swear it used to.

Another option is to have a single activity be the MAIN/LAUNCHER one. Have it set up with android:theme="@style/Theme.NoDisplay", so it does not have a UI. Have it make the determination, in Java, in onCreate(), which of your "real" entry-point activities is appropriate for the given screen size, perhaps using the same bool resources I cited above. Have it then call startActivity() to pass control to the right activity and call finish() on itself (so the user does not encounter an invisible activity on the BACK stack). This technique is also used in cases where there is no way to control this via the manifest, such as "do we have Maps V1 or not" where you have android:required="false" on the <uses-library> element.

Answer 2

Why to take so much pain? Just go about designing separate apps for phone and tablet (make sure they have the same package name). Multiple APKs is what you should look for:

Although we encourage you to develop and publish a single APK that supports as many device
configurations as possible, doing so is sometimes not possible. To help you publish your
application for as many devices as possible, Google Play allows you to publish multiple 
APKs under the same application listing. Google Play then supplies each APK to the 
appropriate devices based on configuration support you've declared in the manifest file of 
each APK. 

Here's a link: http://developer.android.com/google/play/publishing/multiple-apks.html

Answer 3

On first launch of your application, you can programmatically check if your device is a tablet or phone. If it is a phone, you can programmatically add a shortcut to the home screen, and specify the Intent the launcher should use, in order to go to the correct Activity.

First, in your Manifest, you will have only one launcher, but you will have an Activity with no intent filters that will be opened from the programmatically-created shortcut.

Next, in your launcher Activity's onCreate, check if the you have already created the shortcut. From what I have read, the best way to do this is using a boolean value in SharedPreferences:

SharedPreferences prefs = getSharedPreferences(getPackageName(), MODE_PRIVATE);
if (!prefs.getBoolean("shortcut", false)) {
    if (!isTablet(this)) {
        createShortcut();
    }
    prefs.edit().putBoolean("shortcut", true).commit();
}
else {
    //if the shortcut has already been made, see if that is what was used to open this app
    if (getIntent() != null) {
        if (getIntent().getBooleanExtra("shortcut", false)) {
            //the shortcut was used, so open the other Activity:
            Intent shortcut = new Intent(this, OtherActivity.class);
            startActivity(shortcut);
        }
    }
}

Next, you need to define what you call a tablet. This is based on the density-independent pixels of the screen. For example, to call devices with 7-inch screens tablets, this number is 600. For larger devices - such as a 10-inch screen, this number is 720. Store this number in a variable:

private static final int TABLET_DP = 600;

Then add the methods used above:

public static boolean isTablet(Context context) {
    WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);\
    Display display = wm.getDefaultDisplay();
    DisplayMetrics outMetrics = new DisplayMetrics();
    display.getMetrics(outMetrics);
    float density  = context.getResources().getDisplayMetrics().density;
    float dpWidth  = outMetrics.widthPixels / density;
    return dpWidth >= TABLET_DP;
}

private void createShortcut() {

    //this is the intent that will be used when the shortcut is clicked.
    Intent shortcutIntent = new Intent(Intent.ACTION_MAIN);
    shortcutIntent.setClassName(this, this.getClass().getName());
    shortcutIntent.putExtra("shortcut", true);

    //this is the intent used to create the shortcut.
    Intent intent = new Intent();
    intent.putExtra(Intent.EXTRA_SHORTCUT_INTENT, shortcutIntent);
    intent.putExtra(Intent.EXTRA_SHORTCUT_NAME, getString(R.string.app_name));//or however you want the shortcut to be labeled.
    Parcelable iconResource = Intent.ShortcutIconResource.fromContext(
            this,  R.drawable.ic_launcher);//or whatever you want the icon to be
    intent.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, iconResource);
    intent.setAction("com.android.launcher.action.INSTALL_SHORTCUT");

    //tell Android to create the shortcut
    context.sendBroadcast(intent);
}

Finally, be sure you have the correct permissions to install shortcuts:

<uses-permission android:name="com.android.launcher.permission.INSTALL_SHORTCUT"></uses-permission>

Answer 4

I may be beating a dead horse here, but what about using layout aliases?

Use Layout Aliases

Answer 5

You will need to make multiple apks, one for tabs and one for phones, the only difference will be the manifest file in those apks. Rest you can manage with code.