Get launcher activity from installed apk

if you do know the package:

final PackageManager pm = getPackageManager();

        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
        mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

        List appList = pm.queryIntentActivities(mainIntent, 0);
        Collections.sort(appList, new ResolveInfo.DisplayNameComparator(pm));

        for (ResolveInfo temp : appList) {

            Log.v("my logs", "package and activity name = "
                    + temp.activityInfo.packageName + "    "
                    + temp.activityInfo.name);

        }

if you know the package:

PackageManager pm = getPackageManager();
Intent intent=pm.getLaunchIntentForPackage(pacakgeName);
startActivity(intent);