How to make an android app which contains three other apps?

How to make an android app which contains three other apps? On the main app, the icons of those three apps are displayed and by clicking on an icon, the coresponding app launches.

Like I want to display the icons of facebook, google map and gmail on the main app and by clicking 开发者_运维问答on the facebook icon, facebook opens up.

Should I make a single APK file for all apps? How?

Do you mean that you want the icons to appear in the main apps list? If so, what you need to do is add these lines:

<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />

To whatever activity you want to appear in the main app drawer.

Anyway, this seems like a bad idea except in a few rare circumstances where each 'app' is distinct from the other apps, but it doesn't make sense to have one of them without having them all.

If they are essentially one app, do the world a favor and make only one icon. If they are many apps that can exist independently of each other, make separate apk files for them so that the user can install what he/she wants.

I quite didnt get what u were trying to do, if you have the source codes of the other 3 apps, you could extract the activities and make the main app call the activitied (will require some more configuration though) , if you just have the apk, i think you can request the user to install all the 3 after the main app has been installed, and call them by using intents. :) Good luck on this

Take a look at this question: bundle multiple apps in one app