How to open WhatsApp using an Intent in your Android App

Using the 2018 api:

String url = "https://api.whatsapp.com/send?phone="+number;Intent i = new Intent(Intent.ACTION_VIEW);i.setData(Uri.parse(url));startActivity(i);

This code working for me

String contact = "+00 9876543210"; // use country code with your phone number    String url = "https://api.whatsapp.com/send?phone=" + contact;    try {         PackageManager pm = context.getPackageManager();         pm.getPackageInfo("com.whatsapp", PackageManager.GET_ACTIVITIES);         Intent i = new Intent(Intent.ACTION_VIEW);         i.setData(Uri.parse(url));         startActivity(i);                                } catch (PackageManager.NameNotFoundException e) {    Toast.makeText(MainActivity.activity, "Whatsapp app not installed in your phone", Toast.LENGTH_SHORT).show();    e.printStackTrace();    }

This works perfectly 2021

Expansion of short forms:

numero = number phone

mensaje= message to send

private void openWhatsApp(String numero,String mensaje){    try{        PackageManager packageManager = getActivity().getPackageManager();        Intent i = new Intent(Intent.ACTION_VIEW);        String url = "https://api.whatsapp.com/send?phone="+ numero +"&text=" + URLEncoder.encode(mensaje, "UTF-8");        i.setPackage("com.whatsapp");        i.setData(Uri.parse(url));        if (i.resolveActivity(packageManager) != null) {            startActivity(i);        }else {            KToast.errorToast(getActivity(), getString(R.string.no_whatsapp), Gravity.BOTTOM, KToast.LENGTH_SHORT);        }    } catch(Exception e) {        Log.e("ERROR WHATSAPP",e.toString());        KToast.errorToast(getActivity(), getString(R.string.no_whatsapp), Gravity.BOTTOM, KToast.LENGTH_SHORT);    }}

Hope, This Helps!