Show compose SMS view in Android

You can use the following code:

startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("sms:"
                        + phoneNumber)));

Make sure you set phoneNumber to the phone number that you want to send the message to

You can add a message to the SMS with (from comments):

Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("sms:" + phoneNumber));     
intent.putExtra("sms_body", message); 
startActivity(intent);