[NavigationAdvancedSample] Even top level destinations show up/back arrow

[ammargitham]

With update to navigation 2.4.0-alpha01, even top level destinations show the up arrow.

Tested on Samsung Galaxy S8. Android 9.

[ammargitham]

Seems the kotlin version of ActionBarOnDestinationChangedListener always sets the actionBar.setDisplayHomeAsUpEnabled to true.

Below diff is from https://android.googlesource.com/platform/frameworks/support/+/5b19fddb91b129168429b3cbf77323414d638b03%5E%21/#F1

-
-    @Override
-    protected void setNavigationIcon(Drawable icon,
-            @StringRes int contentDescription) {
-        ActionBar actionBar = mActivity.getSupportActionBar();
-        if (icon == null) {
-            actionBar.setDisplayHomeAsUpEnabled(false);
-        } else {
-            actionBar.setDisplayHomeAsUpEnabled(true);
-            ActionBarDrawerToggle.Delegate delegate = mActivity.getDrawerToggleDelegate();
-            delegate.setActionBarUpIndicator(icon, contentDescription);
-        }
-    }
-
+    override fun setNavigationIcon(icon: Drawable, @StringRes contentDescription: Int) {
+        val actionBar = activity.supportActionBar
+        require(actionBar != null) {
+            "Activity $activity does not have an ActionBar set via setSupportActionBar()"
+        }
+        actionBar.setDisplayHomeAsUpEnabled(true)
+        val delegate = activity.drawerToggleDelegate
+        require(delegate != null) {
+            "Activity $activity does not have an DrawerToggleDelegate set"
+        }
+        delegate.setActionBarUpIndicator(icon, contentDescription)
+    }

Seems the parameter icon was set to non-null initially and then later made nullable in https://android.googlesource.com/platform/frameworks/support/+/d5f4ba078465516da538bcf96042a33e0cb6edd8/navigation/navigation-ui/src/main/java/androidx/navigation/ui/ActionBarOnDestinationChangedListener.kt. But the null check was not added back.

[DJDrama]

@ammargitham Guess there are some unexpected bugs in "alpha" version. waiting for "beta"

[kasem-sm]

Update the navigation version to 2.4.0-alpha03 (latest as of 6/23/21)

[DJDrama]

Update the navigation version to 2.4.0-alpha03 (latest as of 6/23/21)

great!