CODEWITHSUNDEEP
androidnavigationviewandroid-navigationview
Soren Stoutner
Soren Stoutner

Reputation: 1433

How to programatically disable and enable items every time an Android NavigationView is displayed

I am moving some menu items from the options menu to the navigation menu. My app uses a NavigationView that is populated by a menu as described at https://developer.android.com/reference/android/support/design/widget/NavigationView.html

One of the items calls webView.goBack() on the WebView in the main activity. When it was placed in the options menu, it was only enabled if webView.canGoBack(). Otherwise, it was disabled (grayed out). To accomplish this, onPrepareOptionsMenu() included the command:

back.setEnabled(webView.canGoBack());

As onPrepareOptionsMenu() is called every time the options menu is about to be displayed, this would update the status of the menu item to correctly reflect the state of the WebView.

However, I have not been able to replicate this behavior with the NavigationView. Is there a method or class similar to onPrepareOptionsMenu() that is called each time the NavigationView is prepared?

PS. Other people who have addressed similar questions have always referred to using a ListView, which was an older method of populating a navigation drawer. This question specifically relates to using a NavigationView with a menu.

Upvotes: 2

Views: 951

Answers (2)

Soren Stoutner
Soren Stoutner

Reputation: 1433

The answer to this question is to add a DrawerListener and override onDrawerStateChanged.

// Create the navigation drawer.
drawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
// The `DrawerTitle` identifies the drawer in accessibility mode.
drawerLayout.setDrawerTitle(GravityCompat.START, getString(R.string.navigation_drawer));

// Listen for touches on the navigation menu.
final NavigationView navigationView = (NavigationView) findViewById(R.id.navigationView);
navigationView.setNavigationItemSelectedListener(this);

// Get handles for `navigationMenu` and the back and forward menu items.  The menu is zero-based, so item 1 and 2 and the second and third items in the menu.
final Menu navigationMenu = navigationView.getMenu();
final MenuItem navigationBackMenuItem = navigationMenu.getItem(1);
final MenuItem navigationForwardMenuItem = navigationMenu.getItem(2);

// The `DrawerListener` allows us to update the Navigation Menu.
drawerLayout.addDrawerListener(new DrawerLayout.DrawerListener() {
    @Override
    public void onDrawerSlide(View drawerView, float slideOffset) {
    }

    @Override
    public void onDrawerOpened(View drawerView) {
    }

    @Override
    public void onDrawerClosed(View drawerView) {
    }

    @Override
    public void onDrawerStateChanged(int newState) {
        // Update the back and forward menu items every time the drawer opens.
        navigationBackMenuItem.setEnabled(webView.canGoBack());
        navigationForwardMenuItem.setEnabled(webView.canGoForward());
    }
});

Upvotes: 2

Doug Stevenson
Doug Stevenson

Reputation: 317760

NavigationView exposes its underlying Menu with getMenu(). You can use that to find menu items and make changes to them.

Upvotes: 0

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