I have an Adapter and a Sub-Fragment. I am using an interface to pass data from the Adapter to the Sub-Fragment. The problem I am having is that I keep getting a Null Pointer Exception. I have read through the various posts here relating to the problem and can't figure out where I went wrong. I get the NPE at the line 'passAdapterVariable.passAdapterVariable(mname)'. Based on what I have read I suspect it may be because I am not properly initializing passAdapterVariable. I have tried initializing it several different ways based on other examples but I keep getting the NPE.
Here is the Adapter
public class MatchAdapter extends RecyclerView.Adapter<MatchAdapter.MatchViewHolder> {
//declaration of variables
private Fragment fragment;
private FragmentManager fragmentManager;
private DiscoverPage discoverPage;
private Context context;
private int size;
private int mposition;
private TextView txt_matchname;
private ImageView img_matchpic;
List<String> maImg = new ArrayList<>();
private String mname;
PassAdapterVariable passAdapterVariable;
public interface PassAdapterVariable {
void passAdapterVariable(String mname);
}
//the constructor
public MatchAdapter(List<String> maImg, int size, Context context, DiscoverPage discoverPage){//, PassAdapterVariable passAdapterVariable) {
this.maImg = maImg;
this.context = context;
this.discoverPage = discoverPage;
this.size = size;
//this.passAdapterVariable = (PassAdapterVariable)context;
}
public MatchAdapter(String mname, Context context) {
this.context = context;
this.passAdapterVariable = (PassAdapterVariable)context;
}
//PassAdapterVariable passAdapterVariable = (PassAdapterVariable) context;
@Override
public MatchAdapter.MatchViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.match_items, parent, false);
MatchViewHolder matchViewHolder = new MatchViewHolder(view, maImg, discoverPage);
return matchViewHolder;
}
@Override
public void onBindViewHolder(MatchViewHolder holder, int position) {
Picasso.with(context).load(maImg.get(position)).into(holder.img_match);
holder.setIsRecyclable(false);
}
@Override
public int getItemCount() {
return maImg.size();
}
//viewholder class
public class MatchViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private static final String TAG = "error";
//declare variables
private DiscoverPage discoverPage;
private ImageView img_match;
//ViewHolder constructor
public MatchViewHolder(View itemView, final List<String> maImg, final DiscoverPage discoverPage) {
super(itemView);
//initialize variables inside the viewholder constructor
this.discoverPage = discoverPage;
img_match = (ImageView) itemView.findViewById(R.id.img_match);
txt_matchname = (TextView) itemView.findViewById(R.id.txt_matchname);
img_matchpic = (ImageView) itemView.findViewById(R.id.img_matchpic);
//set click listener for the img_match
img_match.setOnClickListener(this);
}
@Override
public void onClick(View view) {
if (view == img_match) {
//discoverPage.isHidden();
Fragment currentFragment;
fragment = new ClickedMatch();
fragmentManager = ((AppCompatActivity) context).getSupportFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(android.R.id.content, fragment);
transaction.addToBackStack("DiscoverPage");
if ((currentFragment = ((AppCompatActivity) context).getSupportFragmentManager().findFragmentById(R.id.main_container)) != null) {
transaction.hide(currentFragment);
}
else {
transaction.commit();
}
mname = maImg.get(getAdapterPosition());
mposition = getAdapterPosition();
mname = maImg.get(mposition);
passAdapterVariable.passAdapterVariable(mname);
}
}
}
}
Here is the Sub-Fragment
public class ClickedMatch extends Fragment implements MatchAdapter.PassAdapterVariable{
//declare variables
private Toolbar toolbar;
private TextView txt_matchname;
private TextView txt_matchprice;
private ImageView img_matchpic;
private String mname;
private String imgmatch;
List<String> maImg = new ArrayList<>();
int size;
Context context;
DiscoverPage discoverPage;
private String pname;
private int i;
MatchAdapter.PassAdapterVariable passAdapterVariable;
public ClickedMatch() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_clicked_match, container, false);
//initialize variables
toolbar = (Toolbar) view.findViewById(R.id.toolbar);
((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);//set toolbar as action bar
txt_matchname = (TextView)view.findViewById(R.id.txt_matchname);
img_matchpic = (ImageView)view.findViewById(R.id.img_matchpic);
//setHasOptionsMenu(true);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getActivity().onBackPressed();
}
});
if(((AppCompatActivity)getActivity()).getSupportActionBar()!= null){
((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
((AppCompatActivity)getActivity()).getSupportActionBar().setDisplayShowHomeEnabled(true);
((AppCompatActivity)getActivity()).getSupportActionBar().setHomeButtonEnabled(true);
((AppCompatActivity)getActivity()).getSupportActionBar().setTitle("");
}
// MatchAdapter matAdapter = new MatchAdapter(maImg, size, context, discoverPage,
//passAdapterVariable);
// matAdapter.passAdapterVariable = this;
//passAdapterVariable.passAdapterVariable(mname);
//txt_matchname.setText(pname);
MatchAdapter matAdapter = new MatchAdapter(pname, getContext());
matAdapter.passAdapterVariable = this;
passAdapterVariable(pname);
txt_matchname.setText(pname);
return view;
}
@Override
public void passAdapterVariable(String mname) {
this.pname = mname;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
this.getActivity().finish();
}
return super.onOptionsItemSelected(item);
}
}
Here is the error log
08-13 21:53:49.341 12852-12852/com.test.jack E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.test.jack, PID: 12852
java.lang.NullPointerException: Attempt to invoke interface method 'void com.test.jack.MatchAdapter$PassAdapterVariable.passAdapterVariable(java.lang.String)' on a null object reference
at com.test.jack.MatchAdapter$MatchViewHolder.onClick(MatchAdapter.java:138)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
To add some more context, I have a main activity(UserMainPage). A bottom navigation menu selector replaces the UserMainPage with a fragment(DiscoverPage).
DiscoverPage calls the adapter(MatchAdapter). A button click on DiscoverPage replaces DiscoverPage with a sub-fragment(ClickedMatch).
I am trying to pass a variable from MatchAdapter to ClickedMatch.