Android支持v23.1.0更新中断NavigationView get / find标头

Question

I have been using the v23.0.1 support library until now with no problems. Now when I switch to the new v23.1.0 library I am getting a null pointer on widgets in the drawer layout.

mNavigationView = (NavigationView) findViewById(R.id.navigation_view);    
TextView username = (TextView) mNavigationView.findViewById(R.id.username_textView);
//       ^^^^^^^^ is now null when using new library
// which causes the following to fail
username.setText(mUser.getName());

activity layout

<?xml version="1.0" encoding="utf-8"?>
<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"
    tools:context=".MainActivity">

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

    <include layout="@layout/toolbar" />

    ...

</LinearLayout>

<android.support.design.widget.NavigationView
    android:id="@+id/navigation_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/drawer_header"
    app:menu="@menu/drawer_items" />

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

drawer_header.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:fresco="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="150dp"
android:orientation="vertical">

   <TextView
    android:id="@+id/username_textView"
    android:layout_width="match_parent"
    android:layout_height="0dp" />

    ...

</LinearLayout>

Simply changing the gradle file to use the older version makes it work fine instantly so I don't think there is anything horribly wrong with my code. I checked out the revisions in the update and didn't see anything that I would think to cause this.

Surely this will be affecting others also, any clues?

Answer 1

With the design library v 23.1.0 the NavigationView works with a RecyclerView .
Also the Header is now a type of row.

It means that the header could not be immediately available in the view hierarchy .
It can cause issues if you are using methods like navigationView.findViewById(XXX) to get a view inside the header.

There is a bug in the Google Tracker .

EDIT 12/10/2015: Design library 23.1.1

The 23.1.1 introduces a new API for retrieving header views for NavigationView with getHeaderView()

BEFORE 23.1.1

workaround fot 23.1.0 can be to use a addOnLayoutChangeListener . Somenthing like:

navigationView.addOnLayoutChangeListener( new View.OnLayoutChangeListener()
{
    @Override
    public void onLayoutChange( ... )
    {
        navigationView.removeOnLayoutChangeListener( this );

        View view = navigationView.findViewById( ... );
    }
} );

Another possible workaround are:

• remove the app:headerLayout attribute from the xml, and then add the header programatically.

• Inflate the headerView programmatically.

Use somenthing like this:

View headerLayout = navigationView.inflateHeaderView(R.layout.navigation_header);
headerLayout.findViewById(xxx);

Answer 2

It appears attaching the header view to the navigation drawer using xml is currently broken. The solution is to inflate and attach the view manually.

activity layout

<android.support.design.widget.NavigationView
    android:id="@+id/navigation_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/drawer_header" <!-- remove this line -->
    app:menu="@menu/drawer_items" />

Then in your code inflate and attach the header by doing the following.

NavigationView navigationView = (NavigationView) findViewById(R.id.navigation_view);
View drawerHeader = navigationView.inflateHeaderView(R.layout.drawer_header);

TextView username = (TextView) drawerHeader.findViewById(R.id.username_textView);

Answer 3

在新的NavigationView ，标题现在是RecyclerView的行类型，以便您或任何人通过其id找到view ，您需要解决它并使用addOnLayoutChangeListener监听器，然后您可以找到我知道应该记录的view在某个地方但是android就像meh！

Answer 4

it is a bug at 23.1.0

23.1.1 fixed

https://plus.google.com/+AndroidDevelopers/posts/ebXLByBiEBU

Answer 5

I have updated build tools from Android sdk manager, then 23.1.0 is also working fine for me.

I am using

buildToolsVersion "23.0.2"

before this it was 23.0.1.

and there is no need of using

(View)navigationView.findViewById(R.id.idOfViewFromHeaderView);

In your activity you can directly use

(View)findViewById(R.id.idOfViewFromHeaderView);