How to call whatsapp as an Intent from my app on Android?
Intent sendIntent = new Intent(Intent.ACTION_VIEW);
            sendIntent.putExtra("sms_body", "The SMS text");
            sendIntent.setType("vnd.android-dir/mms-sms");

            startActivity(sendIntent);

Intent i = new Intent(android.content.Intent.ACTION_SEND);

i.setType("text/plain");
i.putExtra(Intent.EXTRA_SUBJECT, "Subject");
i.putExtra(Intent.EXTRA_TEXT, "Message body");

startActivity(Intent.createChooser(i, "Share dialog title"));