How to change text of a TextView in navigation drawer header?

Question

I want to change the text of a TextView inside the navigation drawer header. But I get this error:

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

---

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> 

MainActivity.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");     } 

How can I do this?

Answer 1

Use function getHeaderView on your navigationView:

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");