Julia Julia - 4 months ago 46
Android Question

Navigation Drawer RecyclerView close my app after the back button is pressed

I'm trying to implement material design to my app and is following a tutorial. The problem I have is when the RecyclerView is open, and I click on the "back" button on the phone, it would close my app instead of closing the RecyclerView. How do I close the RecyclerView instead of exit the app? Thanks.

Here's the code

public class MainActivity extends AppCompatActivity implements FragmentDrawer.FragmentDrawerListener {

private static String TAG = MainActivity.class.getSimpleName();

private Toolbar mToolbar;
private FragmentDrawer drawerFragment;

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

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

setSupportActionBar(mToolbar);
getSupportActionBar().setDisplayShowHomeEnabled(true);

drawerFragment = (FragmentDrawer)
getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
drawerFragment.setDrawerListener(this);

// display the first navigation drawer view on app launch
displayView(0);
}


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

if(id == R.id.action_search){
Toast.makeText(getApplicationContext(), "Search action is selected!", Toast.LENGTH_SHORT).show();
return true;
}

return super.onOptionsItemSelected(item);
}

@Override
public void onDrawerItemSelected(View view, int position) {
displayView(position);
}

private void displayView(int position) {
Fragment fragment = null;
String title = getString(R.string.app_name);
switch (position) {
case 0:
fragment = new HomeFragment();
title = getString(R.string.title_home);
break;
case 1:
fragment = new FriendsFragment();
title = getString(R.string.title_friends);
break;
case 2:
fragment = new MessagesFragment();
title = getString(R.string.title_messages);
break;
default:
break;
}

if (fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.container_body, fragment);
fragmentTransaction.commit();

// set the toolbar title
// getSupportActionBar().setTitle(title);
}
}
}


Here is layout xml

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">


<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<LinearLayout
android:id="@+id/container_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">

<include
android:id="@+id/toolbar"
layout="@layout/toolbar" />
</LinearLayout>

<FrameLayout
android:id="@+id/container_body"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1" />


</LinearLayout>


<fragment
android:id="@+id/fragment_navigation_drawer"
android:name="test.materialdesign.com.materialdesign.activity.FragmentDrawer"
android:layout_width="@dimen/nav_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
app:layout="@layout/fragment_navigation_drawer"
tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>


enter image description here

Answer

To close drawer, when back button is pressed, you have to override onBackPressed(), this way:

@Override
public void onBackPressed() {

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