From http://cloudchen.logdown.com/posts/159965/how-to-find-android-app-package-name-use-to-sent-message-through-intent

Line.java

Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_TEXT, "Your Message Here");
sendIntent.setType("text/plain");
sendIntent.setPackage("Package Name Here");
startActivity(sendIntent);