How to close navigation DrawerLayout onBackPressed in Navigation Controls Fragment

Question

I have created an Androidx project with Navigation pattern. Now I want to close drawerLayout onBackPressed() in fragment. And also I want to set OnClickListener to drawer menu items to my custom menu there is no way I guess to override the onBackPressed() in fragment.

I want to know how I can achieve this?

Here is my drawer:

<androidx.drawerlayout.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:id="@+id/drawerLayoutHome"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.navigation.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="350dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@color/colorPrimaryDark"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:itemIconTint="@color/white"
        app:itemTextColor="@color/white"
        app:menu="@menu/activity_main_drawer"/>

</androidx.drawerlayout.widget.DrawerLayout>

I want to achieve this:

override fun onBackPressed() {

    if (drawerLayoutHome.isDrawerOpen(GravityCompat.END)) {
        drawerLayoutHome.closeDrawer(GravityCompat.END)
    } else {
        super.onBackPressed()
    }
}

But this is for Activity, how to achieve this in Fragment?

Answer 1

Hello there you can do it by getting your fragment in activity and override onbackpress with kotlin code

This is your backpress function and in this you can get your nav host and then you can check your current fragment or the fragment you want to open drawer in .

override fun onBackPressed() {

    val navHostFragment = supportFragmentManager.findFragmentById(R.id.fragmentHomeHost)
    val completeFragmentList = navHostFragment?.childFragmentManager?.fragments

    if (completeFragmentList != null) {
        when {
            completeFragmentList[0] is HomeFragment -> {
                val home = (completeFragmentList[0] as HomeFragment)


            }
            else -> super.onBackPressed()
        }
    }

    if (drawerLayoutHome.isDrawerOpen(GravityCompat.START)) {
        drawerLayoutHome.closeDrawer(GravityCompat.START)
    } else {
        super.onBackPressed()
    }
}

And here is hoe you can get selection item listener

override fun onNavigationItemSelected(item: MenuItem): Boolean {
    drawerLayoutHome.closeDrawer(GravityCompat.START)

    return true
}

Answer 2

You can do that within a Fragment by implementing OnBackStackChangedListener on your drawer activity.
Then, link your drawer with ActionBarDrawerToggle and override onBackStackChanged() and synchronize your drawer toggle.

Here is the full snippet:

public class MainActivity extends AppCompatActivity implements FragmentManager.OnBackStackChangedListener {


    private DrawerLayout drawer;
    private ActionBarDrawerToggle toggle;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //Bind listener here
        getSupportFragmentManager().addOnBackStackChangedListener(this);
        drawer = findViewById(R.id.drawer_layout);
        toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        toggle.setToolbarNavigationClickListener(view -> onBackPressed());
        drawer.addDrawerListener(toggle);
        toggle.syncState();

    }


    //Override fragment backstack lister method 
    @Override
    public void onBackStackChanged() {
        //toggle.setDrawerIndicatorEnabled(getSupportFragmentManager().getBackStackEntryCount() == 0);
        //getSupportActionBar().setDisplayHomeAsUpEnabled(getSupportFragmentManager().getBackStackEntryCount() > 0);
        toggle.syncState();
    }

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

I hope this will help you.