How to show/Hide Navigation Drawer programmatically

Question

How can I use button to show/hide Navigation Drawer, I have used this SO link to create and manage Navigation Drawer.

Now i am using (Swipe to right from left - to show)

Answer 1

To open the Drawer

DrawerLayout drawer = findViewById(R.id.drawer_layout);
drawer.openDrawer(GravityCompat.START);

To close the drawer

DrawerLayout drawer = findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);