NullPointerException Attempt to invoke virtual method int java util ArrayList size on a null object reference

Question

I m a newbie to Fragments and custom ListView adapters  Can anyone give me a hand please   I ve got my Fragment where I have my ListView  public class RecordingListFragment extends Fragment implements OnItemClickListener        ListView mListView      TextView emptyView      Button options  delete edit      ArrayList lt String gt  recordings   null      RecordingsListAdapter mAdapter       public RecordingListFragment                 Override     public View onCreateView LayoutInflater inflater  ViewGroup container Bundle savedInstanceState            View rootView   inflater inflate R layout recording list fragment  container false            options    Button  rootView findViewById R id options           edit    Button  rootView findViewById R id edit           delete    Button  rootView findViewById R id delete           mListView    ListView  rootView findViewById R id list           emptyView    TextView  rootView findViewById R id empty             mAdapter   new RecordingsListAdapter this  recordings           mListView setAdapter mAdapter           mListView setEmptyView emptyView           mListView setOnItemClickListener this            return rootView            and my xml for it   lt LinearLayout xmlns android  http   schemas android com apk res android      xmlns tools  http   schemas android com tools      xmlns android1  http   schemas android com apk res android      android id    id recording list fragment      android layout width  match parent      android layout height  match parent      android background   ffffff      android orientation  vertical  gt        lt RelativeLayout         android layout height  50dp          android layout width  match parent          android orientation  horizontal          android background   drawable title   gt            lt TextView             android1 id    id title              android1 layout width  wrap content              android1 layout height  50dp              android1 layout alignParentTop  true              android1 layout centerHorizontal  true              android1 layout marginStart  80dp              android1 gravity  center              android1 text   string app name              android1 textAlignment  center              android1 textColor   000000              android1 textStyle  bold    gt        lt  RelativeLayout gt        lt FrameLayout         android layout height  wrap content          android layout width  match parent  gt            lt ListView             android id    id list              android animateLayoutChanges  true              android layout width  match parent              android layout height  match parent   gt           lt  --  android divider   null -- gt             lt TextView             android id    id empty              android layout width  match parent              android layout height  match parent              android gravity  center              android text   string empty list text              android paddingLeft  30dp              android paddingRight  30dp              android paddingTop  180dp    gt        lt  FrameLayout gt   lt  LinearLayout gt    and I ve got my custom list item   lt  xml version  1 0  encoding  utf-8   gt   lt LinearLayout xmlns android  http   schemas android com apk res android      android layout height  wrap content      android layout width  match parent      android orientation  horizontal   gt        lt CheckedTextView         android id    id textView          android layout width  fill parent          android layout height   android attr listPreferredItemHeight          android textAppearance   android attr textAppearanceLarge          android gravity  center vertical          android checkMark   android attr listChoiceIndicatorSingle          android paddingLeft  6dip          android paddingRight  6dip          android textColor   000000            gt     lt  LinearLayout gt    and finally  my Adapter  public class RecordingsListAdapter  extends BaseAdapter       Context ctx      LayoutInflater lInflater      ArrayList lt String gt  recordings       RecordingsListAdapter Context context  ArrayList lt String gt  products            ctx   context          recordings   products          lInflater    LayoutInflater  ctx          getSystemService Context LAYOUT INFLATER SERVICE              public RecordingsListAdapter RecordingListFragment recordingListFragment      ArrayList lt String gt  recordings               TODO Auto-generated constructor stub              Override     public int getCount             return recordings size                 Override     public Object getItem int position            return recordings get position                Override     public long getItemId int position            return position               Override     public View getView int position  View convertView  ViewGroup parent             View view   convertView          if  view    null                view   lInflater inflate R layout custom list item  parent  false                      return view             and when I run this  I get this null pointer  11-26 11 00 45 352  E AndroidRuntime 10191   java lang RuntimeException  Unable to start activity ComponentInfo d recordings RecordingsActivity   java lang NullPointerException  Attempt to invoke virtual method  int java util ArrayList size    on a null object reference 11-26 11 00 45 352  E AndroidRuntime 10191      at android app ActivityThread performLaunchActivity ActivityThread java 2298  11-26 11 00 45 352  E AndroidRuntime 10191      at android app ActivityThread handleLaunchActivity ActivityThread java 2360  11-26 11 00 45 352  E AndroidRuntime 10191      at android app ActivityThread access 800 ActivityThread java 144  11-26 11 00 45 352  E AndroidRuntime 10191      at android app ActivityThread H handleMessage ActivityThread java 1278  11-26 11 00 45 352  E AndroidRuntime 10191      at android os Handler dispatchMessage Handler java 102  11-26 11 00 45 352  E AndroidRuntime 10191      at android os Looper loop Looper java 135  11-26 11 00 45 352  E AndroidRuntime 10191      at android app ActivityThread main ActivityThread java 5221  11-26 11 00 45 352  E AndroidRuntime 10191      at java lang reflect Method invoke Native Method  11-26 11 00 45 352  E AndroidRuntime 10191      at java lang reflect Method invoke Method java 372  11-26 11 00 45 352  E AndroidRuntime 10191      at com android internal os ZygoteInit MethodAndArgsCaller run ZygoteInit java 899  11-26 11 00 45 352  E AndroidRuntime 10191      at com android internal os ZygoteInit main ZygoteInit java 694  11-26 11 00 45 352  E AndroidRuntime 10191   Caused by  java lang NullPointerException  Attempt to invoke virtual method  int java util ArrayList size    on a null object reference 11-26 11 00 45 352  E AndroidRuntime 10191      at recordings RecordingsListAdapter getCount RecordingsListAdapter java 36  11-26 11 00 45 352  E AndroidRuntime 10191      at android widget ListView setAdapter ListView java 487  11-26 11 00 45 352  E AndroidRuntime 10191      at recordings RecordingListFragment onCreateView RecordingListFragment java 47  11-26 11 00 45 352  E AndroidRuntime 10191      at android app Fragment performCreateView Fragment java 2053  11-26 11 00 45 352  E AndroidRuntime 10191      at android app FragmentManagerImpl moveToState FragmentManager java 894  11-26 11 00 45 352  E AndroidRuntime 10191      at android app FragmentManagerImpl moveToState FragmentManager java 1067  11-26 11 00 45 352  E AndroidRuntime 10191      at android app BackStackRecord run BackStackRecord java 833  11-26 11 00 45 352  E AndroidRuntime 10191      at android app FragmentManagerImpl execPendingActions FragmentManager java 1452  11-26 11 00 45 352  E AndroidRuntime 10191      at android app Activity performStart Activity java 5948  11-26 11 00 45 352  E AndroidRuntime 10191      at android app ActivityThread performLaunchActivity ActivityThread java 2261  11-26 11 00 45 352  E AndroidRuntime 10191          10 more   Thank you in advance

User · Answer

This issue is due to ArrayList variable not being instantiated. Need to declare "recordings" variable like following, that should solve the issue;

ArrayList<String> recordings = new ArrayList<String>();

this calls default constructor and assigns empty string to the recordings variable so that it is not null anymore.

User · Answer

You should initialize yours recordings  You are passing to adapter null   ArrayList lt String gt  recordings   null    You are passing this null

User · Answer

Change    mAdapter   new RecordingsListAdapter this  recordings     to   mAdapter   new RecordingsListAdapter getActivity    recordings     and also make sure that recordings  null at  mAdapter   new RecordingsListAdapter this  recordings

[android] NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference

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