单击后关闭导航抽屉

Question

点击打开新NavigationDrawer后，如何关闭Fragment。我尝试了一些事情，但却无法让它发挥作用

MainActivity.java

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

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

    if(savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .replace(R.id.container, BookAFragment.newInstance())
                .commit();
    }

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);



    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);
}

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


@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();


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

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {

    int id = item.getItemId();

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

        Toast.makeText(getApplicationContext(),"Book A Selected", Toast.LENGTH_SHORT).show();
        BookAFragment fragment = new BookAFragment();
        android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
        fragmentTransaction.replace(R.id.container,fragment);
        fragmentTransaction.commit();
        return true;

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

        Toast.makeText(getApplicationContext(),"Book B Selected", Toast.LENGTH_SHORT).show();
        BookBFragment fragment = new BookBFragment();
        android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
        fragmentTransaction.replace(R.id.container,fragment);
        fragmentTransaction.commit();
        return true;

    }

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