Android Error Attempt to invoke virtual method void android app ActionBar on a null object reference

Question

I have a code module which implements viewpager with navigation drawer  however  when I run the code I get the following error  01-26 09 20 02 958  D AndroidRuntime 18779   Shutting down VM 01-26 09 20 02 959  E AndroidRuntime 18779   FATAL EXCEPTION  main 01-26 09 20 02 959  E AndroidRuntime 18779   Process  com example tabwithslidingdrawer  PID  18779 01-26 09 20 02 959  E AndroidRuntime 18779   java lang RuntimeException  Unable to start activity ComponentInfo com example tabwithslidingdrawer com example tabwithslidingdrawer MainActivity   java lang NullPointerException  Attempt to invoke virtual method  void android app ActionBar setDisplayHomeAsUpEnabled boolean   on a null object reference 01-26 09 20 02 959  E AndroidRuntime 18779      at android app ActivityThread performLaunchActivity ActivityThread java 2314  01-26 09 20 02 959  E AndroidRuntime 18779      at android app ActivityThread handleLaunchActivity ActivityThread java 2388  01-26 09 20 02 959  E AndroidRuntime 18779      at android app ActivityThread access 800 ActivityThread java 148  01-26 09 20 02 959  E AndroidRuntime 18779      at android app ActivityThread H handleMessage ActivityThread java 1292  01-26 09 20 02 959  E AndroidRuntime 18779      at android os Handler dispatchMessage Handler java 102  01-26 09 20 02 959  E AndroidRuntime 18779      at android os Looper loop Looper java 135  01-26 09 20 02 959  E AndroidRuntime 18779      at android app ActivityThread main ActivityThread java 5312  01-26 09 20 02 959  E AndroidRuntime 18779      at java lang reflect Method invoke Native Method  01-26 09 20 02 959  E AndroidRuntime 18779      at java lang reflect Method invoke Method java 372  01-26 09 20 02 959  E AndroidRuntime 18779      at com android internal os ZygoteInit MethodAndArgsCaller run ZygoteInit java 901  01-26 09 20 02 959  E AndroidRuntime 18779      at com android internal os ZygoteInit main ZygoteInit java 696  01-26 09 20 02 959  E AndroidRuntime 18779   Caused by  java lang NullPointerException  Attempt to invoke virtual method  void android app ActionBar setDisplayHomeAsUpEnabled boolean   on a null object reference 01-26 09 20 02 959  E AndroidRuntime 18779      at com example tabwithslidingdrawer MainActivity onCreate MainActivity java 95  01-26 09 20 02 959  E AndroidRuntime 18779      at android app Activity performCreate Activity java 5953  01-26 09 20 02 959  E AndroidRuntime 18779      at android app Instrumentation callActivityOnCreate Instrumentation java 1128  01-26 09 20 02 959  E AndroidRuntime 18779      at android app ActivityThread performLaunchActivity ActivityThread java 2267  01-26 09 20 02 959  E AndroidRuntime 18779          10 more    09 20 02 959  E AndroidRuntime 18779   Caused by  java lang NullPointerException  Attempt to invoke virtual method  void android app ActionBar setDisplayHomeAsUpEnabled boolean   on a null object reference 01-26 09 20 02 959  E AndroidRuntime 18779       at com example tabwithslidingdrawer MainActivity onCreate MainActivity java 95     points to this line     enabling action bar app icon and behaving it as a toggle button         getActionBar   setDisplayHomeAsUpEnabled true           getActionBar   setHomeButtonEnabled true     entire code http   pastebin com u1K72fr7  My manifest   lt  xml version  1 0  encoding  utf-8   gt   lt manifest xmlns android  http   schemas android com apk res android      package  com example tabwithslidingdrawer      android versionCode  1      android versionName  1 0   gt        lt uses-sdk         android minSdkVersion  8          android targetSdkVersion  19    gt        lt application         android allowBackup  true          android icon   drawable ic launcher          android label   string app name          android theme   style Theme Tabwithpager   gt           lt activity             android name  com example tabwithslidingdrawer MainActivity              android label   string app name   gt               lt intent-filter gt                   lt action android name  android intent action MAIN    gt                    lt category android name  android intent category LAUNCHER    gt               lt  intent-filter gt           lt  activity gt       lt  application gt    lt  manifest gt    android theme   style Theme Tabwithpager    code http   pastebin com EFQLzRej                                                                     EDIT UPDATE   What I learnt from this  Whenever such an error occurs  1  Check what kind of Activity is being used  is it a simple android app Activity or an AppCompatActivity or an ActionBarActivity and so on   2  Check if your activity type which is extended falls under the compat category  example android app based Activity Fragment are non appCompat types  whereas android support v4 app Fragment or android support v4 app ActivityCompat are appCompat based  if it falls under appCompat we use getSupportActionBar   else for android app types we can use getActionBar    3  Check the theme applied to the activity in question in the manifest file  example  In the manifest file if theme applied is say android theme   android style Theme Holo Dialog  getActionBar   will work  but if theme applied for the activity in the manifest is as follows android theme   style Theme AppCompat Light  then you have to use getSupportActionBar

User · Answer

In my case is because of styles xml set the wrong parent theme  i e  NoActionBar theme of course getSupportActionbar   is null    lt style name  AppTheme  parent  Theme AppCompat Light NoActionBar  gt    Changed it to something else fixed it    lt style name  AppTheme  parent  Theme AppCompat Light DarkActionBar  gt

User · Answer

Please add after Toolbar   Toolbar toolbar   findViewById R id toolbar   setSupportActionBar toolbar   getSupportActionBar   hide

User · Answer

if u have creat a new toolbar then apply check that u have apply the  method setSupportActionBar    it will defenetly help you

User · Answer

I am a new to Android App development  I faced this error and spend almost 5 hours trying to fix it  Finally  i found out the following was the root cause for this issue and if anyone to face this issue again in the future  please give this a read   I was trying to create a Home Activitiy with a Video Background  for which i had to change the parent theme from the default setting of Theme AppCompat Light DarkActionBar to Theme AppCompat Light NoActionBar  This worked fine for the Home Activity  but when i set a new button with a onclicklistener to navigate to another Activity  where i had set a custom text to the Action Bar  this error is thrown   So  what i ended up doing was to create two themes and assigned them to the activities as follows   Theme AppCompat Light DarkActionBar - for Activities with Action Bar  default  Theme AppCompat Light NoActionBar - for Activities without Action Bar    I have made the following changes to make fix the error    Defining the themes in styles xml   lt style name  AppTheme  parent  Theme AppCompat Light NoActionBar  gt       lt item name  colorPrimary  gt  color colorPrimary lt  item gt       lt item name  colorPrimaryDark  gt  color colorPrimaryDark lt  item gt       lt item name  colorAccent  gt  color colorAccent lt  item gt   lt  style gt    lt style name  DefaultTheme  parent  Theme AppCompat Light DarkActionBar  gt       lt item name  colorPrimary  gt  color colorPrimary lt  item gt       lt item name  colorPrimaryDark  gt  color colorPrimaryDark lt  item gt       lt item name  colorAccent  gt  color colorAccent lt  item gt   lt  style gt   Associating the Activities to their Respective Themes in AndroidManifest xml   lt activity android name   Payment      android theme   style DefaultTheme   gt    lt activity android name   WelcomeHome      android theme   style AppTheme NoActionBar  gt

User · Answer

The Up Button is usually activated for Low-level Activities  In your manifest I only see the MainActivity  I don t think it makes sense to activate the up button for the main activity  Create an activity  then in the manifest add the parentActivityName attribute  Then activate the up button on the activity s onCreate method  This should help  https   developer android com training appbar up-action html

User · Answer

Whenever such an error occurs  Try to check Following Things   Check what kind of Activity is being used  is it a simple android app Activity or an AppCompatActivity or an ActionBarActivity and so on  Check if your activity type which is extended falls under the compat category   example android app based Activity Fragment are non appCompat types  whereas android support v4 app Fragment or android support v4 app ActivityCompat are appCompat based  if it falls under appCompat we use getSupportActionBar   else for android app types we can use getActionBar     Check the theme applied to the activity in question in the manifest file   example  In the manifest file if theme applied is say android theme   android style Theme Holo Dialog  getActionBar   will work  but if theme applied for the activity in the manifest is as follows android theme   style Theme AppCompat Light  then you have to use getSupportActionBar

User · Answer

Try this hope it will work  my code is works fine  Toolbar toolbar   findViewById R id toolbar1   setSupportActionBar toolbar    getSupportActionBar   setDisplayHomeAsUpEnabled true   getSupportActionBar   setHomeButtonEnabled true   getSupportActionBar   setTitle

User · Answer

Your code is throwing on com example tabwithslidingdrawer MainActivity onCreate MainActivity java 95               enabling action bar app icon and behaving it as toggle button         getActionBar   setDisplayHomeAsUpEnabled true           getActionBar   setHomeButtonEnabled true     The problem is pretty simple- your Activity is inheriting from the new android support v7 app ActionBarActivity  You should be using a call to getSupportActionBar   instead of getActionBar     If you look above around line 65 of your code you ll see that you re already doing that           actionBar   getSupportActionBar            actionBar setNavigationMode ActionBar NAVIGATION MODE LIST              TODO  Remove the redundant calls to getSupportActionBar                    and use variable actionBar instead         getSupportActionBar   setDisplayHomeAsUpEnabled true           getSupportActionBar   setHomeButtonEnabled true     And then lower down around line 87 it looks like you figured out the same           getSupportActionBar   setTitle                          Html fromHtml   lt font color   black   gt     mTitle     -                                             menutitles 0      lt  font gt                 getActionBar   setTitle mTitle  menutitles 0      Notice how you commented out getActionBar

User · Answer

I know that this question is something old  But this can help many who present this problem   To solve this problem  check if there is a point of nullity  Then apply the corresponding configuration   if getSupportActionBar      null    getSupportActionBar   setDisplayHomeAsUpEnabled true    getSupportActionBar   setHomeButtonEnabled true

User · Answer

I think what you want to do is cast getActivity    For example     AppCompatActivity getActivity    getSupportActionBar   setDisplayHomeAsUpEnabled true    This is what you need to do with the new support libraries  AppCompatActivity has replaced ActionBarActivity

User · Answer

When use AppCompatActivity must call    Toolbar toolbar    Toolbar  findViewById R id toolbar   setSupportActionBar toolbar     Before getSupportActionBar    public class PageActivity extends AppCompatActivity         Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity item           Toolbar toolbar    Toolbar  findViewById R id toolbar           setSupportActionBar toolbar           this getSupportActionBar   setDisplayHomeAsUpEnabled false

User · Answer

in this line in your activity   super onCreate savedInstanceState   setContentView R layout Activity Main     use this   super onCreate savedInstanceState   setContentView R layout         is your activity

User · Answer

Try to check here  res    values    styles xml  make sure that there no code like this   lt item name  windowActionBar  gt false lt  item gt    if there are code like that  you can disable for a while  or erase it

User · Answer

For those still having this issue  my issue was resolved in the AndroidManifest xml file  Where it says  lt activity android name   MainActivity  android theme   style AppTheme NoActionBar  gt   you need to remove NoActionBar  making it  lt activity android name   MainActivity  android theme   style AppTheme  gt   because with NoActionBar set the app doesnt know whether or not it wants an action bar when you call one up inside of MainActivity java

User · Answer

You should try this one  I think it will work       Toolbar toolbar   findViewById R id toolbar1       setSupportActionBar toolbar        mDrawerLayout   findViewById R id drawer layout       mDrawerLayout   findViewById R id drawer layout       mDrawerLayout setDrawerShadow R drawable rectagle with black outer              GravityCompat START       getSupportActionBar   setDisplayHomeAsUpEnabled true       getSupportActionBar   setHomeButtonEnabled true        mDrawerToggle   new ActionBarDrawerToggle this  mDrawerLayout              toolbar  R string navigation drawer close              R string navigation drawer close            public void onDrawerClosed View view                invalidateOptionsMenu                       public void onDrawerOpened View drawerView                invalidateOptionsMenu

User · Answer

In my case I had the same error but my mistake was that I didn t declare my Toolbar   So  before I use getSupportActionBar I had to find my toolbar and set the actionBar      appbar    Toolbar  findViewById R id toolbar       setSupportActionBar appbar        getSupportActionBar   setHomeAsUpIndicator R drawable ic nav menu       getSupportActionBar   setDisplayHomeAsUpEnabled true

User · Answer

I got the same error once  I created a template for a default toolbar  toolbar xml  and then in another view I created a collapsable toolbar   I required to add the collapsable toolbar to a view that show some information of the user like whatsapp   but the method findViewById was referencing the default toolbar id toolbar   not the collapsable one  id toolbar as well  yes  I wrote the same id to both toolbar  so when I tried to access the activity the app crashed showing me the error   I fixed the error by changing the id of the collapsable toolbar to id col toolbar and the error gone away and my app worked perfectly

User · Answer

If anybody wants to use android app ActionBar and android app Activity you should change the app theme in styles xml  for example    lt style name  AppTheme  parent  android Theme Holo Light DarkActionBar  gt    The problem is you could be using an AppCompat theme   On the other hand  if you want to use android support v7 app ActionBar and you extend your activity with AppCompatActivity then you must use an AppCompat theme to avoid this issue  for example    lt style name  AppTheme  parent  Theme AppCompat Light DarkActionBar  gt    Hope this helps

User · Answer

If you encounter this error    java lang NullPointerException  Attempt to invoke virtual method  void androidx appcompat app ActionBar setTitle  java lang CharSequence   on a null object reference      Just use   setSupportActionBar  toolbar

User · Answer

For anyone else who has a BaseActivity  and a child that extends from it  make sure the super onCreate   is called first before you do anything  The old Activity would work if you called super onCreate   afterwards    Child extends Activity - could call super after you did stuff   Override protected void onCreate Bundle savedInstanceState        getActionBar   setDisplayHomeAsUpEnabled true       super onCreate savedInstanceState     Child extends AppCompatActivity - ya gotta call super first   Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState     do this first     getSupportActionBar   setDisplayHomeAsUpEnabled true

User · Answer

If you are using android app ActionBar and android app Activity you should change the app theme in application tag    lt  application      android theme   android style Theme Holo Light  gt

User · Answer

The best solution do this in your Oncreate method   ActionBar actionBar   getSupportActionBar             if actionBar    null               actionBar setDisplayHomeAsUpEnabled true                followed by a new class   Override     public boolean onOptionsItemSelected MenuItem item             int id   item getItemId             if id    android R id home               onBackPressed                return true                     return super onOptionsItemSelected item

User · Answer

when you extend appcompatActivity then use  this getSupportActionBar   setDisplayHomeAsUpEnabled true     and when you extend ActionBar then use   this getActionBar   setDisplayHomeAsUpEnabled true     dont forget to call this function in oncreate after initializing the toolbar actionbar

User · Answer

Try doing this                   getSupportActionBar   setDisplayHomeAsUpEnabled true                   getSupportActionBar   setHomeButtonEnabled true                   actionBar   getSupportActionBar                    actionBar setNavigationMode ActionBar NAVIGATION MODE LIST     Instead of this   actionBar   getSupportActionBar                    actionBar setNavigationMode ActionBar NAVIGATION MODE LIST                    getSupportActionBar   setDisplayHomeAsUpEnabled true                   getSupportActionBar   setHomeButtonEnabled true

[android] Android Error [Attempt to invoke virtual method 'void android.app.ActionBar' on a null object reference]

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