如何更改导航抽屉标题中 TextView 的文本？

Question

我想更改导航抽屉标题中 TextView 的文本。但我收到此错误：

java.lang.NullPointerException：尝试在空对象引用上调用虚方法“void android.widget.TextView.setText(java.lang.CharSequence)”

---

activity_main.xml

 <?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">

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

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

        <FrameLayout
            android:id="@+id/frame_container"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </LinearLayout>

    <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 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/slide_nav_bar"
    android:gravity="bottom"
    android:orientation="vertical"
    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">

    <ImageView
        android:id="@+id/tvHeaderIcon"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:paddingTop="@dimen/nav_header_vertical_spacing"
        android:src="@android:drawable/sym_def_app_icon" />

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

    <TextView
        android:id="@+id/tvHeaderName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

主活动.java

 TextView tvHeaderName;

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

    tvHeaderName= (TextView) findViewById(R.id.tvHeaderName);
    tvHeaderName.setText("Saly");
}

我怎样才能做到这一点？

原文由 Salar Rastari 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

在您的导航视图上使用函数 getHeaderView：

 NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
View headerView = navigationView.getHeaderView(0);
TextView navUsername = (TextView) headerView.findViewById(R.id.navUsername);
navUsername.setText("Your Text Here");

原文由 Bereket Gobeze 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 2

这是代码的 Kotlin 版本，希望它能帮助那里的人。

 val navigationView : NavigationView  = findViewById(R.id.nav_view)
val headerView : View = navigationView.getHeaderView(0)
val navUsername : TextView = headerView.findViewById(R.id.txtUserName)
val navUserEmail : TextView = headerView.findViewById(R.id.txtEmail)

navUsername.text = username.toString()
navUserEmail.text = email.toString()

原文由 Siyabonga Dube 发布，翻译遵循 CC BY-SA 4.0 许可协议