Android : How to set AppCompat Toolbar back button

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);

ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
    actionBar.setHomeButtonEnabled(true);
    actionBar.setDisplayHomeAsUpEnabled(true);
}
...
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.empty_menu, menu);

    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem menuItem)
{

    switch (menuItem.getItemId())
    {
        case android.R.id.home:
            onBackPressed();
            return true;

        default:
            return super.onOptionsItemSelected(menuItem);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="?attr/actionBarSize"
    android:background="?attr/colorPrimary"
    local:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    local:popupTheme="@style/ThemeOverlay.AppCompat.Light" />