我设置了应用程序，所以当我点击Recycler View上的视图时，电影图像会正确转换为Activity B.现在，当我尝试填充活动B中的对象信息（如情节等）时，我得到了一个错误说我在onBindViewHolder中的内容为null。我必须遗漏某些东西因为我之前设置应用程序的方式（一张卡上的所有信息）所有内容都被正确查询并显示出来。当我决定更改并将信息发送到活动B时，这一切都开始发生了。
这是适配器
public class MoviesAdapter extends RecyclerView.Adapter<MoviesAdapter.MyViewHolder> {
private List<MovieData> moviesList;
private Context context;
private ClickListener clickListener;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
public MoviesAdapter(Context context, List<MovieData> moviesList) {
this.moviesList = moviesList;
this.context = context;
}
public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView title, plot, releaseDate, rating;
public ImageView thumb;
public NetworkImageView moviePic;
public MyViewHolder(View view) {
super(view);
view.setOnClickListener(this);
title = (TextView) view.findViewById(R.id.name);
plot = (TextView) view.findViewById(R.id.plot);
releaseDate = (TextView) view.findViewById(R.id.releaseDate);
rating = (TextView) view.findViewById(R.id.rating);
thumb = (ImageView) view.findViewById(R.id.thumb);
moviePic = (NetworkImageView) view.findViewById(R.id.profilePic);
}
@Override
public void onClick(View v) {
//context.startActivity(new Intent(context,DisplayActivity.class));
if (clickListener != null) {
clickListener.itemClicked(v, getAdapterPosition());
}
}
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.movie_row, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
MovieData movie = moviesList.get(position);
holder.title.setText(movie.getTitle());
holder.plot.setText(movie.getPlot());
holder.releaseDate.setText(movie.getReleaseDate());
holder.rating.setText(movie.getRating());
Float nRating = Float.parseFloat(holder.rating.getText().toString());
if (nRating > 6.5) {
holder.thumb.setImageResource(R.drawable.ic_thumbs_up);
} else {
holder.thumb.setImageResource(R.drawable.ic_thumbdown);
}
holder.moviePic.setImageUrl(movie.getImage(), imageLoader);
}
@Override
public int getItemCount() {
return moviesList.size();
}
//Interface and method to help with clicks
public interface ClickListener {
void itemClicked(View view, int position);
}
public void setClickListener(ClickListener clickListener) {
this.clickListener = clickListener;
}
这是mainActivity
public class MainActivity extends AppCompatActivity implements MoviesAdapter.ClickListener {
private static final String TAG = MainActivity.class.getSimpleName();
static final int SETTINGS_INTENT_REPLY = 1;
private MoviesAdapter mAdapter;
private List<MovieData> mData = new ArrayList<>();
private RecyclerView recyclerView;
private GridLayoutManager gridLayoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//check Sdk Level
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
mAdapter = new MoviesAdapter(this, mData);
mAdapter.setClickListener(this);
gridLayoutManager = new GridLayoutManager(this,2);
recyclerView.setLayoutManager(gridLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(mAdapter);
refreshMovie();
}
@Override
public void onActivityResult(int settingsRequestCode, int settingsResultcode, Intent resultData) {
super.onActivityResult(settingsRequestCode, settingsResultcode, resultData);
if (settingsRequestCode == SETTINGS_INTENT_REPLY) {
refreshMovie();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
Intent settingsIntent = new Intent(this, SettingsActivity.class);
startActivityForResult(settingsIntent, SETTINGS_INTENT_REPLY);
return true;
}
return super.onOptionsItemSelected(item);
}
public void refreshMovie() {
// Get a reference to the ConnectivityManager to check state of network connectivity
ConnectivityManager connMgr = (ConnectivityManager)
this.getSystemService(Context.CONNECTIVITY_SERVICE);
// Get details on the currently active default data network
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
// If there is a network connection, fetch data
if (networkInfo != null && networkInfo.isConnected()) {
mData.clear();
networkCall();
} else {
mData.clear();
Snackbar snackbar = Snackbar
.make(recyclerView, "Network Error", Snackbar.LENGTH_INDEFINITE)
.setAction("Retry", new View.OnClickListener() {
@Override
public void onClick(View view) {
refreshMovie();
}
});
snackbar.show();
}
}
/**
* Parsing json reponse and passing the data to feed view list adapter
*/
public void parseJsonFeed(JSONObject response) {
final String POSTER_BEGIN_URL = "http://image.tmdb.org/t/p/w500/";
try {
JSONArray feedArray = response.getJSONArray("results");
for (int i = 0; i < feedArray.length(); i++) {
JSONObject feedObj = (JSONObject) feedArray.get(i);
MovieData item = new MovieData();
item.setTitle(feedObj.getString("original_title"));
// Image might be null sometimes
String image = feedObj.isNull("poster_path") ? null : feedObj
.getString("poster_path");
String POSTER_URL = POSTER_BEGIN_URL + image;
item.setImage(POSTER_URL);
item.setPlot(feedObj.getString("overview"));
item.setRating(feedObj.getString("vote_average"));
item.setReleaseDate(feedObj.getString("release_date"));
mData.add(item);
}
// notify data changes to list adapater
mAdapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
public void networkCall() {
// We first check for cached request
Cache cache = AppController.getInstance().getRequestQueue().getCache();
String order;
SharedPreferences sharedPrefs =
PreferenceManager.getDefaultSharedPreferences(this);
String orderType = sharedPrefs.getString(
getString(R.string.pref_order_key),
getString(R.string.pref_most_popular));
if (orderType.equals(getString(R.string.pref_top_rated))) {
order = "top_rated";
} else {
order = "popular";
}
String URL_FEED = "https://api.themoviedb.org/3/movie/" + order + "?api_key=" + BuildConfig.OPEN_MOVIE_API_KEY;
Cache.Entry entry = cache.get(URL_FEED);
if (entry != null) {
// fetch the data from cache
try {
String data = new String(entry.data, "UTF-8");
try {
parseJsonFeed(new JSONObject(data));
} catch (JSONException e) {
e.printStackTrace();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
} else {
// making fresh volley request and getting json
JsonObjectRequest jsonReq = new JsonObjectRequest(Request.Method.GET,
URL_FEED, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
VolleyLog.d(TAG, "Response: " + response.toString());
if (response != null) {
parseJsonFeed(response);
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
}
});
// Adding request to volley request queue
AppController.getInstance().addToRequestQueue(jsonReq);
}
}
@Override
public void itemClicked(View view, int position) {
view.setTransitionName("mImage");
MovieData movie = mData.get(position);
Intent intent = new Intent(this, DisplayActivity.class);
intent.putExtra("MoviePoster", movie.getImage());
intent.putExtra("Title", movie.getTitle());
intent.putExtra("rDate", movie.getReleaseDate());
intent.putExtra("plot", movie.getPlot());
intent.putExtra("rating", movie.getRating());
ActivityOptionsCompat optionsCompat = ActivityOptionsCompat.makeSceneTransitionAnimation(this,view, view.getTransitionName());
getApplicationContext().startActivity(intent,optionsCompat.toBundle());
}
}
这是活动B
public class DisplayActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display);
ImageLoader imageLoader = AppController.getInstance().getImageLoader();
TextView nTitle = (TextView) findViewById(R.id.name);
TextView nDate = (TextView) findViewById(R.id.releaseDate);
TextView nRating = (TextView) findViewById(R.id.rating);
TextView nPlot = (TextView) findViewById(R.id.plot);
NetworkImageView nProfilePic = (NetworkImageView) findViewById(R.id.profilePic);
// The detail Activity called via intent. Inspect the intent for data.
Bundle bundle = getIntent().getExtras();
if (bundle != null) {
//intent
String movieImage = bundle.getString("MoviePoster");
//intent
String movieName = bundle.getString("title");
//intent
String movieDate = bundle.getString("rDate");
//intent
String movieRating = bundle.getString("rating");
//intent
String moviePlot = bundle.getString("plot");
//set views
nProfilePic.setImageUrl(movieImage, imageLoader);
nTitle.setText(movieName);
nDate.setText(movieDate);
nRating.setText(movieRating);
nPlot.setText(moviePlot);
}
}
}
这是logcat
04-12 14:01:22.349 23413-23413/com.app.sparkimagination.moviesmoviesmovies E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.app.sparkimagination.moviesmoviesmovies, PID: 23413
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at adapter.MoviesAdapter.onBindViewHolder(MoviesAdapter.java:78)
at adapter.MoviesAdapter.onBindViewHolder(MoviesAdapter.java:27)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6356)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6389)
at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5335)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5598)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5440)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5436)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2224)
at android.support.v7.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:556)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1511)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:595)
at android.support.v7.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:170)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3583)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3312)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3844)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:437)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2678)
at android.view.View.layout(View.java:16630)
at android.view.ViewGroup.layout(ViewGroup.java:5437)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2171)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1931)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:606)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThr
先谢谢
movie_row注意持有者中的所有其他视图都在activity_display xml
中<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:tag="cards main container">
<android.support.v7.widget.CardView
android:id="@+id/card_view"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
card_view:cardCornerRadius="2dp"
card_view:cardElevation="5dp"
card_view:cardUseCompatPadding="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<com.android.volley.toolbox.NetworkImageView
android:id="@+id/profilePic"
android:transitionName="@string/transition_string"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:layout_weight="1"
/>
</LinearLayout>
</android.support.v7.widget.CardView>
显示所有信息
的xmlScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="1"
tools:context=".DisplayActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.android.volley.toolbox.NetworkImageView
android:id="@+id/profilePic"
android:layout_width="match_parent"
android:layout_height="262dp"
android:scaleType="fitCenter"
android:transitionName="@string/transition_string" />
<TextView
android:id="@+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="2">
<ImageView
android:id="@+id/thumb"
android:layout_width="0dp"
android:layout_height="75dp"
android:layout_weight="1"
tools:src="@drawable/ic_thumbs_up"
/>
<TextView
android:id="@+id/rating"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:textAlignment="center"
android:textSize="30dp"
android:layout_weight="1"
tools:text="9.0"/>
</LinearLayout>
<TextView
android:id="@+id/plot"
android:layout_width="match_parent"
android:layout_height="173dp" />
<TextView
android:id="@+id/releaseDate"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
答案 0 :(得分：0)
这里的问题是MyViewHolder类和onBindViewHolder()方法引用并调用movie_row xml中不包含的视图的方法。例如，尝试查找R.id.plot，然后在onBindViewholder()尝试调用holder.plot.setText()。 movie_row中没有带有id图的TextView，因此您会收到NullPointerException并崩溃。
据推测，您之前确实拥有其他视图，然后在创建第二个活动时将其删除。
要解决此问题的两个主要选择是要包含您在movie_row.xml中尝试引用的所有视图，如果您确实希望它们显示在RecyclerView中，或者它们并不意味着在那里然后从MyViewHolder类和onBindViewHolder()方法中删除它们。