android - 抽屉导航 : How do I set the selected item at startup?

Question

我的代码完美运行:每次单击抽屉导航中的项目时，都会选择该项目。

当然，我想使用默认 fragment (主页)启动应用程序，但 Navigation Drawer 没有选择该项目。如何以编程方式选择该项目？

public class BaseApp extends AppCompatActivity {

    //Defining Variables
    protected String LOGTAG = "LOGDEBUG";
    protected Toolbar toolbar;
    protected NavigationView navigationView;
    protected DrawerLayout drawerLayout;

    private DateManager db = null;

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

        navigationView = (NavigationView) findViewById(R.id.navigation_view);


        // set the home/dashboard at startup

        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
        fragmentTransaction.replace(R.id.frame, new DashboardFragment());
        fragmentTransaction.commit();

        setNavDrawer();
    }

    private void setNavDrawer(){

        // Initializing Toolbar and setting it as the actionbar
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        //Initializing NavigationView

        //Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

            // This method will trigger on item Click of navigation menu
            @Override
            public boolean onNavigationItemSelected(MenuItem menuItem) {


                //Checking if the item is in checked state or not, if not make it in checked state

                // I THINK THAT I NEED EDIT HERE...

                if (menuItem.isChecked()) menuItem.setChecked(false);
                else menuItem.setChecked(true);

                //Closing drawer on item click
                drawerLayout.closeDrawers();


                //Check to see which item was being clicked and perform appropriate action
                switch (menuItem.getItemId()) {    

                    //Replacing the main content with ContentFragment 

                    case R.id.home:

                        DashboardFragment dashboardFragment = new DashboardFragment();
                        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
                        fragmentTransaction.replace(R.id.frame, dashboardFragment,"DASHBOARD_FRAGMENT");
                        fragmentTransaction.commit();
                        return true;
[...]

我认为我需要在这里编辑:

if (menuItem.isChecked()) menuItem.setChecked(false);
                    else menuItem.setChecked(true);

或在应用启动时的 onCreate 中使用 FragmentTransaction。

感谢您的支持。

Answer 1

使用下面的代码:

navigationView.getMenu().getItem(0).setChecked(true);

调用setNavDrawer();

后调用该方法

getItem(int index) 方法获取 MenuItem 然后您可以在该 MenuItem 上调用 setChecked(true); ，你剩下要做的就是找出默认的元素索引，并将0替换为该索引。

您可以通过调用选择(突出显示)项目

onNavigationItemSelected(navigationView.getMenu().getItem(0));

这是一个引用链接:http://thegeekyland.blogspot.com/2015/11/navigation-drawer-how-set-selected-item.html

编辑 不适用于 nexus 4，支持库修订版 24.0.0。我建议使用

navigationView.setCheckedItem(R.id.nav_item);

下面的@kingston 回答了。