我有一个简单的适配器,它使用2个基于字符串的数组列表。由于某些原因,我得到了一个NullPointerException,尽管我确信信息是通过的。
我的适配器。
public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.ViewHolder> {
private ArrayList<String> names = new ArrayList<>();
private ArrayList<String> details = new ArrayList<>();
private Context mContext;
public MovieAdapter(ArrayList<String> names, ArrayList<String> details, Context mContext) {
this.names = names;
this.details = details;
this.mContext = mContext;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.detail_view, parent, false);
ViewHolder holder = new ViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
holder.name.setText(names.get(position));
holder.detail.setText(details.get(position));
}
@Override
public int getItemCount() {
return names.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
private TextView name;
private TextView detail;
private ConstraintLayout cl;
public ViewHolder(@NonNull View itemView) {
super(itemView);
name = itemView.findViewById(R.id.name);
detail = itemView.findViewById(R.id.detial);
cl = itemView.findViewById(R.id.layout);
}
}
}
我的REST调用和recylerView初始化活动(添加了REST调用以防止问题出现):
// ArrayList<String> namesArray = new ArrayList<>(Arrays.asList("Rated:", "Released:", "Runtime:", "Genre:", , "Writer:", "Actors:", "Plot:", "Language:", "Country:"));
ArrayList<String> namesArray = new ArrayList<>();
namesArray.add("Rated:");
namesArray.add("Released:");
namesArray.add("Runtime:");
namesArray.add("Genre:");
namesArray.add("Director:");
namesArray.add("Writer:");
namesArray.add("Actors:");
namesArray.add("Plot");
namesArray.add("Language:");
namesArray.add("Country");
trazi.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Call<Movie> call;
movieApi = ApiClient.getClient().create(MovieApi.class);
if (paramYear.getText().toString().matches("")) {
call = movieApi.getDetails(key, paramName.getText().toString(), null);
} else {
call = movieApi.getDetails(key, paramName.getText().toString(), Integer.parseInt(paramYear.getText().toString()));
}
call.enqueue(new Callback<Movie>() {
@Override
public void onResponse(Call<Movie> call, Response<Movie> response) {
Toast.makeText(getApplication().getApplicationContext(), " valja", Toast.LENGTH_LONG).show();
movie = response.body();
// ArrayList<String> details = new ArrayList<>(Arrays.asList(movie.getRated(), movie.getReleased(), movie.getRuntime(), movie.getGenre(), movie.getDirector(), movie.getWriter(), movie.getActors(), movie.getPlot(), movie.getLanguage(), movie.getCountry()));
ArrayList<String> details = new ArrayList<>();
details.add(movie.getRated());
details.add(movie.getReleased());
details.add(movie.getRuntime());
details.add(movie.getGenre());
details.add(movie.getDirector());
details.add(movie.getWriter());
details.add(movie.getActors());
details.add(movie.getPlot());
details.add(movie.getLanguage());
details.add(movie.getCountry());
Picasso.get().load(movie.getPoster()).fit().centerInside().into(image);
image.setVisibility(View.VISIBLE);
title.setText(movie.getTitle());
title.setVisibility(View.VISIBLE);
recyclerView = findViewById(R.id.layout);
movieAdapter = new MovieAdapter(namesArray, details, getApplication().getApplicationContext());
recyclerView.setAdapter(movieAdapter);
recyclerView.setLayoutManager(new LinearLayoutManager(getApplication().getApplicationContext()));
}
所以...
Picasso.get().load(movie.getPoster()).fit().centerInside().into(image);
和
title.setText(movie.getTitle());
完美地工作,所以信息被传递给适配器,我试着用两种不同的方式初始化数组列表,以备不时之需。还是没有成功。有什么想法,问题出在哪里?
编辑:我的错误日志。
2020-05-24 17:20:22.600 27595-27595/com.example.cetvrtizadatak E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.cetvrtizadatak, PID: 27595
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
at com.example.cetvrtizadatak.MainActivity$1$1.onResponse(MainActivity.java:115)
at retrofit2.DefaultCallAdapterFactory$ExecutorCallbackCall$1.lambda$onResponse$0$DefaultCallAdapterFactory$ExecutorCallbackCall$1(DefaultCallAdapterFactory.java:81)
at retrofit2.-$$Lambda$DefaultCallAdapterFactory$ExecutorCallbackCall$1$3wC8FyV4pyjrzrYL5U0mlYiviZw.run(Unknown Source:6)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6702)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:911)
你的NullPointerException发生在你试图访问recyclerView对象的一个成员时,这意味着它的值可能是空的。
看了你的代码,我可以推测你传递的id不是你的recyclerView,而是一个布局对象。
仔细检查一下,在你的布局xml文件中,给回收器View的id是否就是你调用findViewById时引用的那个。