Can I make the user agree to a legal disclaimer before installing an Android App?

I'm 开发者_StackOverflow社区about ready to market my first Android App (from a US Google Checkout/Merchant account with US bank account etc.), and I would like to have the user at least agree to some kind of simple liability disclaimer before he/she can install the app.

To your knowledge, is it possible, and if so, what would be the best way to do this?

Your help and tips are greatly appreciated.

When you say "before he/she can install the app" I guess you mean that in the same screen that allows users to install apps you want to put a disclaimer. Well, I think it's not possible. In fact, an application can be installed in different ways (from third party apps, or by using abd install on a rooted handset).

So, my suggestion is to place that disclaimer in the main activity. You can save the user decision somewhere (the easiest way is a preference). That way, you can check whether the user has accepted the disclaimer. Of course, if the user does not accept, you just don't let him/her use your app.

Simple example

public class MainActivity extends Activity {
    public static final String PREFS_NAME = "user_conditions";

    @Override
    protected void onCreate(Bundle state){         
       super.onCreate(state);
       // bla bla bla

       // Check whether the user has already accepted
       SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
       boolean accepted = settings.getBoolean("accepted", false);
       if( accepted ){
           // do what ever you want... for instance:
           startActivity(new Intent(this, RealApp.class));
       }else{
           // show disclaimer....
           // for example, you can show a dialog box... and,
           // if the user accept, you can execute something like this:

           // We need an Editor object to make preference changes.
           // All objects are from android.context.Context
           SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
           SharedPreferences.Editor editor = settings.edit();
           editor.putBoolean("accepted", true);
               // Commit the edits!
           editor.commit();
       }
    }
}

Here's how I implemented the Dialog according to Cristian's example:

In the activity class, I created this method:

    protected Dialog onCreateDialog(int id){
    // show disclaimer....
    // for example, you can show a dialog box... 
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("LEGAL DISCLAIMER: ... ")
           .setCancelable(false)
           .setPositiveButton("Agree", new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int id) {
                   // and, if the user accept, you can execute something like this:
                   // We need an Editor object to make preference changes.
                   // All objects are from android.context.Context
                   SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
                   SharedPreferences.Editor editor = settings.edit();
                   editor.putBoolean("accepted", true);
                   // Commit the edits!
                   editor.commit();                    
               }
           })
           .setNegativeButton("Disagree", new DialogInterface.OnClickListener() {
               public void onClick(DialogInterface dialog, int id) {
                    nm.cancel(R.notification.running); // cancel the NotificationManager (icon)
                    System.exit(0);
               }
           });
    AlertDialog alert = builder.create();
    return alert;
}

At the beginning of the onCreate() method, I added these lines:

    // Check whether the user has already accepted
    SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
    boolean accepted = settings.getBoolean("accepted", false);
    if( accepted ){
        // do what ever you want... for instance:
    }else{
        showDialog(0);
    }

Cheers, Chris