如何根据活动/视图更改导航抽屉中的选定项目？

Question

我有一个导航抽屉活动以及可以进行的其他活动。 我希望根据活动选择导航抽屉中的项目，或查看任何内容。

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Intent intent = new Intent(view.getContext(), MainAddMedActivity.class);
                /*EditText editText = (EditText) findViewById(R.id.search_medicament);
                String medicament_search = editText.getText().toString();*/
                /*intent.putExtra(EXTRA_MESSAGE, medicament_search);*/
                startActivity(intent);
            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

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


    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }


        /*navigationView.getMenu().getItem(0).setChecked(true);*/
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_healthdiary) {

        } else if (id == R.id.nav_appointment) {

        } else if (id == R.id.nav_physician) {

        } else if (id == R.id.nav_protocol) {

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;

例如，我进入MainAddMedActivity并按回去。 然后，我需要一些代码来检查我在哪个视图或活动中，并在导航抽屉中选择该项目。

Answer 1

似乎您尚未实现内容区域的切换。 我建议您为此使用片段。 因此，如果您使用片段，请覆盖活动的onAttachFragment，例如：

@Override
public void onAttachFragment(Fragment fragment) {
    super.onAttachFragment(fragment);
    int id;
    if(fragment instanceof HealthDiaryFragment) id = R.id.nav_healthdiary;
    else
    if(fragment instanceof AppointmentFragment) id = R.id.nav_appointment;
    ...
    else return;
    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setCheckedItem(id);
}

另外，修改您的onBackPressed：

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        if(getFragmentManager().getBackStackEntryCount()>1) {
            getFragmentManager().popBackStack();
        }
        else {
            super.onBackPressed();
        }
    }


    /*navigationView.getMenu().getItem(0).setChecked(true);*/
}

这是假设在处理抽屉选择时，您可以通过将碎片推向后堆栈来替换碎片。