I need to close current Intent by Pressing Back and turn to my app

Question

I have an Unity app, that has Android plugin that can launch other applications that installed on my smartphone. Here My Java class:

public class LaunchOtherApp  extends Activity
{
    public static Activity mainActivity;

    protected static final String LOGTAG = "MyApp";

    private Activity currentActivity;  
    private Intent i;
   

    private static final LaunchOtherApp ourInstance = new LaunchOtherApp();
    public static LaunchOtherApp getInstance() {
        return ourInstance;
    }

    public LaunchOtherApp(){
        Log.i(LOGTAG,"Created LaunchOtherApp");

    }

    public void Launch( final String pack)
    {
        mainActivity.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Intent intent = new Intent();
                intent.setPackage(pack);
                currentActivity = UnityPlayer.currentActivity;
                Context context = currentActivity.getApplicationContext();
                PackageManager pm = context.getPackageManager();
                List<ResolveInfo> resolveInfos = pm.queryIntentActivities(intent, 0);
                Collections.sort(resolveInfos, new ResolveInfo.DisplayNameComparator(pm));

                if (resolveInfos.size() > 0)
                {
                    try
                    {


                        ResolveInfo launchable = resolveInfos.get(0);
                        ActivityInfo activity = launchable.activityInfo;
                        ComponentName name = new ComponentName(activity.applicationInfo.packageName, activity.name);
                        i = new Intent(Intent.ACTION_MAIN);
                        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
                        i.setComponent(name);

             
                        context.startActivity(i);
                    }
                    catch (SecurityException e)
                    {
                        intent = getPackageManager().getLaunchIntentForPackage(pack);
                        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
                        intent.addFlags(Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT);
                        intent.addCategory(Intent.CATEGORY_LAUNCHER);


                        startActivity(intent);

                    }
                }
            }
        });
    }
    @Override
    public void onBackPressed() {
     finish();
    }

Launch - it is method that starting when I click on button in my Unity app... pack variable - it is variable that my Java method receive, and in this variable instantiate Application id. For Example I launched Youtube from my app, and when I pressing Back on my phone, I want to close Youtube, and back to my Unity app... I think I must use onBackPressed method that start when I press Back, but what I must write in this method?
finish(); doesn't help me(( Please, help... Thank you in advance!

Answer 1

Actually, YouTube app is a separate app (might be installed) and you cannot modify that app's behavior. On your button press, Launch method is called and assume YouTube app has started. With the intent:

If you use Intent.FLAG_ACTIVITY_NEW_TASK

YouTube app will start in a new task than yours and pressing back will not return to your app.

If you do not use Intent.FLAG_ACTIVITY_NEW_TASK

The new intent (here YouTube) will be launched in the task of calling activity (your app/game) by default and calling activity will go background. So, pressing back will again return to your app/game as you desired. Because back button press always pops from the backstack of the current task.

So, in the try block of your Launch method, removing the following line should help.

i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);

For more information about task and back stack, here is the official doc.

Edit

I missed that you have used application context. But, you have to launch from your calling activity context, otherwise you must use this flag. So, I have modified your Launch method and put it here, just replace your Launch method with following:

/* Method to launch an app with its package name */
public void Launch( final String pack)
{
    mainActivity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            
            // Using activity context instead of application context
            currentActivity = UnityPlayer.currentActivity;
            Context context = currentActivity;
            PackageManager pm = context.getPackageManager();
            
            // Similar code to launch from package name
            Intent intent = pm.getLaunchIntentForPackage(pack);
            if (intent == null) {
                // The activity cannot be found or the package name cannot be recognized
                // Show some message or do something
                Toast.makeText(context, "Cannot launch...", Toast.LENGTH_SHORT).show();
            } else {
                context.startActivity(intent);
            }
        }
    });
}