change text of textView that is included in activity's xml

Question

I'm trying to change textView ,that is, headerLayout of NavigationView in my 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">

    <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:background="#ffffff"
        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>

here is 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:gravity="bottom"
    android:id="@+id/profile_layout"
    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/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/nav_header_vertical_spacing"
        android:src="@drawable/no_login_picture" />

    <TextView
        android:id="@+id/name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="@dimen/nav_header_vertical_spacing"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1" />

    <TextView
        android:id="@+id/profile_surname"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/address" />

    <com.facebook.login.widget.LoginButton
        android:id="@+id/login_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right" />

</LinearLayout>

as you can see nav_header_main is headerLayout of NavigationView. I want to change TextView from nav_header_main.xml Here's my code

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    FacebookSdk.sdkInitialize(this);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    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) drawer.findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    LoginButton loginButton = (LoginButton) navigationView.findViewById(R.id.login_button);

    callbackManager = CallbackManager.Factory.create();
    loginButton.registerCallback(callbackManager, callback);
    loginButton.setReadPermissions(Arrays.asList("public_profile", "user_friends"));

    profileName = (TextView) navigationView.findViewById(R.id.name);
    profileName.setText("LAASASASSSASA");
}

But this code is not working. My Text doesn't change. What I'm missing?

EDIT:

my exception

    java.lang.RuntimeException: Unable to start activity ComponentInfo{food.foodie.com.foodie/food.foodie.com.foodie.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.facebook.login.widget.LoginButton.registerCallback(com.facebook.CallbackManager, com.facebook.FacebookCallback)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.facebook.login.widget.LoginButton.registerCallback(com.facebook.CallbackManager, com.facebook.FacebookCallback)' on a null object reference
at food.foodie.com.foodie.MainActivity.onCreate(MainActivity.java:101)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) 
at android.app.ActivityThread.access$800(ActivityThread.java:144) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5221) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Why are you inflating 'profileLayout'? an Activity onCreate does this for you in setContentView. A simple findViewById() will work here. — TheSunny, Jan 20 '16 at 23:04
I just have edited my code. I try to use only findViewById and I get `Null Pointer Exception` — David, Jan 21 '16 at 18:48
Get an instance of your NavigationView and then try to `findViewById` with that. — TheSunny, Jan 21 '16 at 20:39
Does `com.facebook.login.widget.LoginButton` exist? What if you try with a normal `Button` — TheSunny, Jan 21 '16 at 20:45
`com.facebook.login.widget.LoginButton` exist. As you can see in my `nav_header_main.xml`. When I try with a normal `Button` I get still the same `Null Pointer Exception` — David, Jan 21 '16 at 20:53
Can you post your most recent code so that I may inspect it. — TheSunny, Jan 21 '16 at 21:04
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/101342/discussion-between-david-and-thesunny). — David, Jan 21 '16 at 21:08

score 0 · Answer 1 · answered Jan 21 '16 at 00:01

You don't need to inflate your nav_header_main, the TextView is already included in your main layout, which is set using setContentView, just call findViewById and you're good to go.

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
   setSupportActionBar(toolbar);

   DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
   NavigationView navigationView = (NavigationView) drawer.findViewById(R.id.nav_view);
   navigationView.setNavigationItemSelectedListener(this);

   //No need to inflate
   TextView profileName = (TextView) findViewById(R.id.name);
   profileName.setText("Changed Text!");
}

change text of textView that is included in activity's xml

1 Answers1