Add button to top right in Bottom Navigation Activity

Question

I created an app in Android Studio using the Bottom Navigation Activity template. There is already a top bar with nothing in it. I would like to put a button in the right of the top bar (not a menu, a button). How do I do this?

Answer 1

The easiest solution is to go ahead and create a menu, but make its sole menu item appear always instead of in the overflow menu.

First create a menu xml file with your button as a menu item, and mark it to be shown always so it won't be put in an overflow menu.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item android:id="@+id/action_settings"
        android:title="@string/settings"
        android:icon="@drawable/ic_settings_24dp"
        app:showAsAction="always" />

</menu>

If you switch to putting an App Bar directly in your layout ( see here , and here ), and your button is global to your whole activity (not just for a specific fragment) you can set this menu on your MaterialToolbar in your layout xml using app:menu . Otherwise, you need to set the menu by overriding onCreateOptionsMenu() in your Activity or Fragment:

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        menuInflater.inflate(R.menu.top_bar_menu, menu)
        return true
    }

To respond to button presses from the menu, you override onOptionsItemSelected() :

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        return when (item.itemId) {
            R.id.action_settings -> {
                // do something
                true
            }
            else -> super.onOptionsItemSelected(item)
        }
    }

If you want to do this from a Fragment, call setHasOptionsMenu(true) in your fragment's onViewCreated() , and you can override the same two above functions in your Fragment.