Android ActionBar is always null

Question

I have activity with a navigation box that moves between fragments. Nothing special.

However, I want the action bar to appear at the top of the action. The problem is that I keep getting nullpointerexception for the Actionbar .

I tried the answers from the following pages:

getActionBar returns null

getActionBar () returns Null (AppCompat-v7 21)

None of them worked, so I thought that I would post my own question with my own code.

MainActivity.java

 package com.jampez.smalltalk; import com.jampez.smalltalk.fragments.HomeFragment; import com.jampez.smalltalk.fragments.MessageFragment; import com.jampez.smalltalk.fragments.PreferencesFragment; import com.jampez.smalltalk.fragments.SettingsFragment; import com.jampez.smalltalk.helper.SessionManager; import android.content.Intent; import android.net.Uri; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.support.v4.widget.DrawerLayout; import android.support.v7.app.ActionBar; import android.support.v7.app.ActionBarDrawerToggle; import android.util.Log; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ArrayAdapter; import android.widget.ListView; public class MainActivity extends FragmentActivity { private DrawerLayout mDrawerLayout; private ListView mDrawerList; private ActionBarDrawerToggle mDrawerToggle; private String[] items; int selectedPosition; private SessionManager session; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); getActionBar().setTitle(""); // Session manager session = new SessionManager(getApplicationContext()); if (!session.isLoggedIn()) { // User is already logged in. Take him to main activity Intent intent = new Intent(MainActivity.this, LoginActivity.class); startActivity(intent); finish(); } items = getResources().getStringArray(R.array.menus); // Getting reference to the DrawerLayout mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); mDrawerList = (ListView) findViewById(R.id.drawer_list); /* Creating an ArrayAdapter to add items to mDrawerList */ ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.drawer_list_item, items); mDrawerList.setAdapter(adapter); mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.drawable.ic_drawer, R.string.drawer_open) { /* Called when drawer is closed */ public void onDrawerClosed(View view) { //Put your code here } /* Called when a drawer is opened */ public void onDrawerOpened(View drawerView) { //Put your code here } }; mDrawerLayout.setDrawerListener(mDrawerToggle); // Enabling Home button getActionBar().setHomeButtonEnabled(true); getActionBar().setDisplayHomeAsUpEnabled(true); // Setting item click listener for the listview mDrawerList mDrawerList.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { selectedPosition = position; /* Replace fragment content */ displayView(position); /* Closing the drawer */ mDrawerLayout.closeDrawer(mDrawerList); } }); /* Setting default fragment */ selectedPosition = 0; displayView(0); } private void displayView(int position) { // update the main content by replacing fragments android.app.Fragment fragment = null; Log.i("position", position+""); switch (position) { case 0: fragment = new HomeFragment(); break; case 1: fragment = new MessageFragment(); break; case 2: fragment = new PreferencesFragment(); break; case 3: fragment = new SettingsFragment(); break; case 4: Intent sendIntent = new Intent(); sendIntent.setAction(Intent.ACTION_SEND); sendIntent.putExtra(Intent.EXTRA_TEXT, "This is my text to send."); sendIntent.setType("text/plain"); startActivity(sendIntent); break; case 5: String url = "http://www.example.com"; Intent i = new Intent(Intent.ACTION_VIEW); i.setData(Uri.parse(url)); startActivity(i); break; default: break; } if (fragment != null) { android.app.FragmentManager fragmentManager = getFragmentManager(); android.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); fragmentTransaction.replace(R.id.content_frame, fragment); fragmentTransaction.commit(); // update selected item and title, then close the drawer mDrawerList.setItemChecked(position, true); mDrawerList.setSelection(position); //setTitle(navMenuTitles[position]); mDrawerLayout.closeDrawer(mDrawerList); } else { // error in creating fragment Log.e("MainActivity", "Error in creating fragment"); } } @Override protected void onPostCreate(Bundle savedInstanceState) { super.onPostCreate(savedInstanceState); mDrawerToggle.syncState(); } } 

activity_main.xml

 <android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/drawer_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:theme="@android:style/Theme.WithActionBar" > <!-- The main content view --> <FrameLayout android:id="@+id/content_frame" android:layout_width="match_parent" android:layout_height="match_parent" /> <!-- The navigation drawer list--> <ListView android:id="@+id/drawer_list" android:layout_width="240dp" android:layout_height="match_parent" android:layout_gravity="start" android:background="#111" android:choiceMode="singleChoice" android:divider="@android:color/transparent" android:dividerHeight="0dp" /> </android.support.v4.widget.DrawerLayout> 

HomeFragment.java

 package com.jampez.smalltalk.fragments; import com.jampez.smalltalk.R; import android.app.Fragment; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; public class HomeFragment extends Fragment { public HomeFragment(){} @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_home, container, false); //getActivity().getActionBar().setTitle(R.string.home); return rootView; } } 

fragment_home.xml

 <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#e5e5e5" android:orientation="vertical" > <TextView android:id="@+id/home_text" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_margin="10dp" android:layout_gravity="start|center_vertical" android:text="@string/home"/> </LinearLayout> 

Android manifest

 <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.jampez.smalltalk" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="23" /> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.GET_ACCOUNTS" /> <uses-permission android:name="android.permission.USE_CREDENTIALS" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <!-- To auto-complete the email text field in the login form with the user emails --> <uses-permission android:name="android.permission.READ_PROFILE" /> <uses-permission android:name="android.permission.READ_CONTACTS" /> <application android:name=".app.AppController" android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" /> <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/facebook_app_id" /> <activity android:name=".MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".LoginActivity" android:label="@string/app_name" android:windowSoftInputMode="adjustResize|stateHidden" > </activity> <activity android:name="com.facebook.FacebookActivity" android:configChanges="keyboard|keyboardHidden|screenLayout|screenSize|orientation" android:label="@string/app_name" android:theme="@android:style/Theme.Translucent.NoTitleBar" /> </application> 

styles.xml

 <resources> <!-- Base application theme, dependent on API level. This theme is replaced by AppBaseTheme from res/values-vXX/styles.xml on newer devices. --> <style name="AppBaseTheme" parent="android:Theme.Holo.Light.DarkActionBar"> <!-- Theme customizations available in newer API levels can go in res/values-vXX/styles.xml, while customizations related to backward-compatibility can go here. --> </style> <!-- Application theme. --> <style name="AppTheme" parent="AppBaseTheme"> <!-- All customizations that are NOT specific to a particular API-level can go here. --> <item name="android:actionBarStyle">@style/MyActionBar</item> <item name="android:actionOverflowButtonStyle">@style/MyActionButtonOverflow</item> <item name="drawerArrowStyle">@style/DrawerArrowStyle</item> </style> <style name="DrawerArrowStyle" parent="Widget.AppCompat.DrawerArrowToggle"> <item name="spinBars">true</item> <item name="color">@color/white</item> </style> <style name="MyActionButtonOverflow" parent="android:style/Widget.Holo.ActionButton.Overflow"> <item name="android:color">@color/white</item> </style> <style name="MyActionBar" parent="@android:style/Widget.Holo.Light.ActionBar"> <item name="android:background">#25a0da</item> </style> 

Logcat Output

 11-08 19:17:38.618: E/AndroidRuntime(6347): FATAL EXCEPTION: main 11-08 19:17:38.618: E/AndroidRuntime(6347): Process: com.jampez.smalltalk, PID: 6347 11-08 19:17:38.618: E/AndroidRuntime(6347): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jampez.smalltalk/com.jampez.smalltalk.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2658) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.ActivityThread.access$900(ActivityThread.java:172) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.os.Handler.dispatchMessage(Handler.java:102) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.os.Looper.loop(Looper.java:145) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.ActivityThread.main(ActivityThread.java:5832) 11-08 19:17:38.618: E/AndroidRuntime(6347): at java.lang.reflect.Method.invoke(Native Method) 11-08 19:17:38.618: E/AndroidRuntime(6347): at java.lang.reflect.Method.invoke(Method.java:372) 11-08 19:17:38.618: E/AndroidRuntime(6347): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399) 11-08 19:17:38.618: E/AndroidRuntime(6347): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 11-08 19:17:38.618: E/AndroidRuntime(6347): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setTitle(java.lang.CharSequence)' on a null object reference 11-08 19:17:38.618: E/AndroidRuntime(6347): at com.jampez.smalltalk.MainActivity.onCreate(MainActivity.java:37) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.Activity.performCreate(Activity.java:6221) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119) 11-08 19:17:38.618: E/AndroidRuntime(6347): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2611) 11-08 19:17:38.618: E/AndroidRuntime(6347): ... 10 more 

Answer 1

* First of all, indicate this dependency in the gradle file

 compile 'com.android.support:appcompat-v7:22.2.0' 

* You should expand your activity to AppCompactActivity and start using the toolbar instead of the ActionBar .

* This is how you use the toolbar in MainActivity

 public class MainActivity extends AppCompatActivity { private Toolbar mToolbar; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mToolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(mToolbar); getSupportActionBar().setDisplayShowHomeEnabled(true); } } 

* here's how to add a toolbar to activity_main.xml

 <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="wrap_content" android:minHeight="?attr/actionBarSize" android:background="?attr/colorPrimary" local:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" local:popupTheme="@style/ThemeOverlay.AppCompat.Light" /> 

* your theme should look something like this: styles.xml

 <style name="MyMaterialTheme" parent="MyMaterialTheme.Base"> </style> <style name="MyMaterialTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar"> <item name="windowNoTitle">true</item> <item name="windowActionBar">false</item> <item name="colorPrimary">@color/colorPrimary</item> <item name="colorPrimaryDark">@color/colorPrimaryDark</item> <item name="colorAccent">@color/colorAccent</item> </style> 

make sure you add this style name to the manifest for your application.

* It is better to use v4.app.Fragment instead of using a fragment.

* so you should set the title from the Fragment class

 ((AppCompatActivity)getActivity()).getSupportActionBar().setTitle(R.string.home); 

Refer to this easy-to-understand tutorial, which will undoubtedly help you set up a material navigation box.

If you want to get started quickly without any problems, you can try integrating this third-party library.

Answer 2

If you don't get an ActionBar at all, such as visualy, try rewriting your activity so you can use AppCompatActivity. This thread suggests using ActionbarActivity instead of FragmentActivity. Since ActionbarActivity is deprecated, AppCompatActivity should work just fine .

For a problem with Nullpointer:
Always accept what you use. If you decide to use AppCompat, make sure you extend AppCompatActivity. Double check all import data - you can use a regular fragment instead of the AppCompat version.
Check your styles and make sure you use AppCompat's parents instead of bare. This also includes your action bar. Instead of Widget.Holo.Light.ActionBar use parent="@style/Widget.AppCompat.Light.ActionBar" . Always call getSupportActionBar instead of getActionBar() . Sometimes it may even be necessary to pass the action that you get with getActivity() in the fragment to AppCompatActivity to make sure you get the correct value: ((AppCompatActivity)getActivity()).getSupportActionBar().setTitle(""); .

Answer 3

Okay, so none of the answers gave me much success. However, I managed to display the action bar, but with somewhat limited functionality.

The first thing I did was replace the appcompat_v7 library with android-support-v7-appcompat . This allows me to call the action bar using getActionBar() .

The limitation is related to trying to control aspects of the action bar. I can set the title and icon in order, but if I try to use ActionBarDrawerToggle , I get a NullPointerException . I also noticed that clicking on the action bar does nothing when it usually opens a box.

Answer 4

You tried to put getWindow().requestFeature(Window.FEATURE_ACTION_BAR); in your onCreate() method? It helped me once. Also try changing the theme to Holo