How to select the first item in a navigation drawer and open a fragment on application start

Question

I have created MainActivity with NavigationView. When Activity is opened I want to automatically select the first item in the navigation d

Answer 1

This can be done even better while considering orientation and other configuration changes. We could select whatever nav drawer menuitem depending on whether we are coming from a previous state. Check: For the Navigation drawer wielding Activity:-

public static final String SELECTED_NAV_MENU_KEY = "selected_nav_menu_key";
// The selected grid position
private int mSelectedNavMenuIndex = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_demo);

   ...........................................................

    navigationView.setNavigationItemSelectedListener(this);

    if (savedInstanceState != null) {
        // Recover assets
        mSelectedNavMenuIndex = savedInstanceState.getInt(SELECTED_NAV_MENU_KEY);

        // Recover menu as selected
        MenuItem menuItem = navigationView.getMenu().getItem(mSelectedNavMenuIndex);
        toggleNavMenuItemCheck(menuItem);
        navigationView.getMenu().performIdentifierAction(menuItem.getItemId(), mSelectedNavMenuIndex);
        return;
    } else {
        MenuItem menuItem = navigationView.getMenu().getItem(mSelectedNavMenuIndex);
        toggleNavMenuItemCheck(menuItem);
        navigationView.getMenu().performIdentifierAction(menuItem.getItemId(), mSelectedNavMenuIndex);
    }
}

The toggle method that helps uncheck or check the menu item

private void toggleNavMenuItemCheck(MenuItem menuItem) {
    if (menuItem.isChecked()){
        menuItem.setChecked(false);
    }  else {
        menuItem.setChecked(true);
    }
}

This is how I save the state of the selected menu item. Check:-

@Override
    public boolean onNavigationItemSelected(MenuItem item) {
        int id = item.getItemId();

        switch (id) {
            case R.id.nav_explore:
                showExploreFragment(null);
                mSelectedNavMenuIndex = 0;
                break;
            case R.id.nav_orders:
                mSelectedNavMenuIndex = 1;
                break;
            case R.id.nav_settings:
                mSelectedNavMenuIndex = 2;
                break;
            default:
                showExploreFragment(null);
                mSelectedNavMenuIndex = 0;
        }
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

// Save any important data for recovery
    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(SELECTED_NAV_MENU_KEY, mSelectedNavMenuIndex);
    }

NB: The line with code:

navigationView.getMenu().performIdentifierAction(menuItem.getItemId(), mSelectedNavMenuIndex);

Can be replaced by the code:

onNavigationItemSelected(menuItem);