导航抽屉：如何在启动时设置所选项目？

Question

我的代码工作得很好：每次单击导航抽屉中的一个项目时，该项目就会被选中。

当然，我想用一个默认片段（主页）启动应用程序，但导航抽屉没有选中该项目。如何以编程方式选择该项？

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;
[...]

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

Answer 1

使用下面的代码：

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

在调用setnavdrawer()后调用此方法；

getItem（int index）方法获取menuitem，然后可以调用setchecked（true）；对该menuitem，所要做的就是找出默认的元素索引，并用该索引替换0。

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

下面由@金斯顿回答。