I am developing an android app.
I want to open (just open) WhatsApp from my app.
How can I open WhatsApp from my app?
Did you try this
Intent launchIntent = getPackageManager().getLaunchIntentForPackage("com.whatsapp");
startActivity(launchIntent);
来源：https://stackoverflow.com/questions/29516628/how-to-open-whatsapp-from-other-app