Question

我正在测试android中的Navigation Drawer示例项目，我在导航视图配置文件标题中设置文本时遇到问题。

这是我的代码：

MainActivity.java

@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) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    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);

    TextView text = (TextView) findViewById(R.id.textView);
    texto.setText("HELLO");
}

activity_main.xml中

<?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"
android:fitsSystemWindows="true" tools:openDrawer="start">

<include layout="@layout/app_bar_main" android:layout_width="match_parent"
    android:layout_height="match_parent" />

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

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

nav_header_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="@dimen/nav_header_height"
android:background="@drawable/side_nav_bar"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:theme="@style/ThemeOverlay.AppCompat.Dark" android:orientation="vertical"
android:gravity="bottom">

<ImageView android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:paddingTop="@dimen/nav_header_vertical_spacing"
    android:src="@android:drawable/sym_def_app_icon" android:id="@+id/imageView" />

<TextView android:layout_width="match_parent" android:layout_height="wrap_content"
    android:paddingTop="@dimen/nav_header_vertical_spacing" android:text="Android Studio"
    android:textAppearance="@style/TextAppearance.AppCompat.Body1" />

<TextView android:layout_width="wrap_content" android:layout_height="wrap_content"
    android:text="android.studio@android.com" android:id="@+id/textView" />

</LinearLayout>

当我尝试设置textview的文本时，我总是会收到此错误，并且它只发生在api level 23：

java.lang.NullPointerException: Attempt to invoke virtual method   'void android.widget.TextView.setText(java.lang.CharSequence)' on a null   object reference

如何从主要活动??

更改nav_header_main.xml的Textview文本

提前致谢

Answer 1

现在有了设计支持库的23.1.1版本，您可以使用

View header = navigationView.getHeaderView(0)
TextView text = (TextView) header.findViewById(R.id.textView);

Answer 2

我遇到了同样的问题，并且可以使用此代码来避免它：

    View header = LayoutInflater.from(this).inflate(R.layout.nav_header_main, null);
    navigationView.addHeaderView(header);
    TextView text = (TextView) header.findViewById(R.id.textView);
    text.setText("HELLO");

Answer 3

Orium答案有效，这也可以。

View header = navigationView.inflateHeaderView(R.layout.nav_header_main);
    TextView text = (TextView) header.findViewById(R.id.textView);
    texto.setText("HELLO");

Answer 4

这解决了我的问题

    View headerView = navigationView.inflateHeaderView(R.layout.header_view);

    txt_fullname = (TextView) headerView.findViewById(R.id.txt_fullname);
    txt_email = (TextView) headerView.findViewById(R.id.txt_email);

Answer 5

View headerView=navigationView.getChildAt(0);
TextView tvName=(TextView)hView.findViewById(R.id.name);
TextView tvEmail=(TextView)hView.findViewById(R.id.email);

    tvName.setText(data);
    tvEmail.setText(data);

Answer 6

或者如果您使用此属性：

<android.support.desibn.widget.NavigationView>
    ...
    app:headerLayout="@layout/your_header_layout"/>

你可以：

View header = mNavigationView.getHeaderView(0);
TextView title = (TextView) header.findViewById(R.id.your_title_id);
//Or something else

Answer 7

以上答案是正确的，但在kotlin中，您需要使用findViewById<View>

   val navigationHeader = navigation_view.getHeaderView(0)
        val navigationTitle = navigationHeader.findViewById<View>(R.id.txt_navigation_title) as TextView
        navigationTitle.text = "This is your header"

Android Api 23更改导航视图headerLayout textview

7 个答案: