Question

activity_main

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/recyclerview"
       />


    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/floatingactionbutton"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        />

    <SeekBar
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/seekbar"
        android:layout_above="@+id/floatingactionbutton"/>
</RelativeLayout>

LIST_ITEM

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:orientation="vertical"
    android:layout_height="wrap_content">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/textview"
        android:text="hi"/>
</LinearLayout>

视频

public class Video {
    private String videoUrl;

    public Video() {
    }

    public Video(String videoUrl) {
        this.videoUrl = videoUrl;
    }

    public String getVideoUrl() {
        return videoUrl;
    }

    public void setVideoUrl(String videoUrl) {
        this.videoUrl = videoUrl;
    }

}

VideoAdapter

public class VideoAdapter extends RecyclerView.Adapter<VideoAdapter.MyViewHolder> {

    private List<Video> videoList;
    private Context context;
    public static final String Position="AdapterPosition";

    public VideoAdapter(List<Video> videoList, Context context) {
        this.videoList = videoList;
        this.context = context;
    }

    @Override
    public VideoAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.list_item, null);

        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(VideoAdapter.MyViewHolder holder, int position) {
        Video contacts = videoList.get(position);

        holder.textView.setText("Hi");
        Toast.makeText(context,contacts.getVideoUrl().toString(),Toast.LENGTH_SHORT).show();
    }

    @Override
    public int getItemCount() {

        return videoList.size();
    }

    public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
        public TextView textView;
        private final Context context;

        public MyViewHolder(View itemView) {
            super(itemView);
            context = itemView.getContext();
            textView = (TextView) itemView.findViewById(R.id.textview);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {

        }
    }

}

MainActivity

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

    public static final String ANONYMOUS = "anonymous";
    public static final int RC_SIGN_IN = 1;
    private static final int RC_PHOTO_PICKER = 2;
    private String mUsername;

    // Firebase instance variables
    private FirebaseDatabase mFirebaseDatabase;
    private DatabaseReference mMessagesDatabaseReference;
    private ChildEventListener mChildEventListener;
    private FirebaseAuth mFirebaseAuth;
    private FirebaseAuth.AuthStateListener mAuthStateListener;
    private FirebaseStorage mFirebaseStorage;
    private StorageReference mChatPhotosStorageReference;
    private FirebaseRemoteConfig mFirebaseRemoteConfig;

    private SeekBar seekBar;

    private RecyclerView recyclerView;
    private FloatingActionButton floatingActionButton;
    NotificationCompat.Builder notificationBuilder;
    VideoAdapter videoAdapter;
    List<Video> videoList;

    NotificationManager notificationManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mUsername = ANONYMOUS;
        recyclerView = (RecyclerView) findViewById(R.id.recyclerview);
        floatingActionButton = (FloatingActionButton) findViewById(R.id.floatingactionbutton);
        videoList = new ArrayList();

        // Initialize Firebase components
        mFirebaseDatabase = FirebaseDatabase.getInstance();
        mFirebaseAuth = FirebaseAuth.getInstance();
        mFirebaseStorage = FirebaseStorage.getInstance();
        mFirebaseRemoteConfig = FirebaseRemoteConfig.getInstance();
        seekBar = (SeekBar) findViewById(R.id.seekbar);

        mMessagesDatabaseReference = mFirebaseDatabase.getReference().child("videomessages");
        mChatPhotosStorageReference = mFirebaseStorage.getReference().child("videos");

        mAuthStateListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user != null) {
                    // User is signed in
                    onSignedInInitialize(user.getDisplayName());
                } else {
                    // User is signed out
                    onSignedOutCleanup();
                    startActivityForResult(
                            AuthUI.getInstance()
                                    .createSignInIntentBuilder()
                                    .setIsSmartLockEnabled(false)
                                    .setProviders(
                                            AuthUI.EMAIL_PROVIDER,
                                            AuthUI.GOOGLE_PROVIDER)
                                    .build(),
                            RC_SIGN_IN);
                }
            }
        };


        floatingActionButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                intent.setType("video/*");
                intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
                startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);

            }
        });


        attachDatabaseReadListener();

    }


    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == RC_SIGN_IN) {
            if (resultCode == RESULT_OK) {
                // Sign-in succeeded, set up the UI
                Toast.makeText(this, "Signed in!", Toast.LENGTH_SHORT).show();
            } else if (resultCode == RESULT_CANCELED) {
                // Sign in was canceled by the user, finish the activity
                Toast.makeText(this, "Sign in canceled", Toast.LENGTH_SHORT).show();
                finish();
            }
        } else if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
            Uri selectedImageUri = data.getData();
            new MyAsyncTask().execute(selectedImageUri);
            // Get a reference to store file at chat_photos/<FILENAME>

        }
        ;
    }

    @Override
    protected void onResume() {
        super.onResume();
        mFirebaseAuth.addAuthStateListener(mAuthStateListener);
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (mAuthStateListener != null) {
            mFirebaseAuth.removeAuthStateListener(mAuthStateListener);
        }
    }

    private void onSignedInInitialize(String username) {
        mUsername = username;
        attachDatabaseReadListener();
    }

    private void onSignedOutCleanup() {
        mUsername = ANONYMOUS;

    }

    private void attachDatabaseReadListener() {

        mMessagesDatabaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot snapshot) {
                videoList.clear();
                for (DataSnapshot postSnapshot : snapshot.getChildren()) {

                    Video postSnapshotValue = postSnapshot.getValue(Video.class);
                    if (!videoList.contains(postSnapshotValue)) {
                        videoList.add(postSnapshotValue);
                        Log.i(TAG, "onDataChange: " + videoList);
                    }

                }

                videoAdapter = new VideoAdapter(videoList, getApplicationContext());
                recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));

                recyclerView.setAdapter(videoAdapter);

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {


            }
        });
    }


    public class MyAsyncTask extends AsyncTask<Uri, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

        }

        @Override
        protected Void doInBackground(Uri... params) {
            StorageReference photoRef = mChatPhotosStorageReference.child(params[0].getLastPathSegment());

            // Upload file to Firebase Storage
            photoRef.putFile(params[0])
                    .addOnSuccessListener(MainActivity.this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
                        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                            // When the image has successfully uploaded, we get its download URL
                            //  progressBar.setVisibility(View.VISIBLE);
                            Uri downloadUrl = taskSnapshot.getDownloadUrl();

                            // Set the download URL to the message box, so that the user can send it to the database
                            Video video = new Video(downloadUrl.toString());
                            mMessagesDatabaseReference.push().setValue(video);

                        }
                    }).addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
                @Override
                public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
                    int  progress = (int) ((100 * taskSnapshot.getBytesTransferred()) / taskSnapshot.getTotalByteCount());

                    seekBar.setProgress(progress);

                    notificationBuilder = new NotificationCompat.Builder(getApplicationContext())
                            .setColor(ContextCompat.getColor(getApplicationContext(), R.color.colorPrimary))
                            .setSmallIcon(R.mipmap.ic_launcher)
                            .setContentText("Download in progress")
                            .setContentIntent(contentIntent(getApplicationContext()))
                            .setAutoCancel(true);

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                        notificationBuilder.setPriority(Notification.PRIORITY_HIGH);
                    }

                    notificationManager = (NotificationManager)
                            getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE);

                    for (int incr = progress; incr <= 100; incr += 5) {


                        notificationBuilder.setProgress(100, progress, false);

                        notificationManager.notify(20, notificationBuilder.build());

                    }
                    if(progress>=100){
                        notificationBuilder.setContentText("Download complete").setProgress(0, 0, false);
                        notificationManager.notify(20, notificationBuilder.build());

                    }



                }
            });
           return null;
        }

        @Override
        protected void onPostExecute(Void integer) {
            super.onPostExecute(integer);

            // Do the "lengthy" operation 20 times

        }


    }

    private PendingIntent contentIntent(Context context) {

        Intent startActivityIntent = new Intent(context, MainActivity.class);
        return PendingIntent.getActivity(
                context,
                0,
                startActivityIntent,
                PendingIntent.FLAG_UPDATE_CURRENT);
    }

}

我经历了所有关于此的问题，但没有找到这个问题的答案。我在我的gradle文件中添加了recyclelerview库。我无法弄清楚我错过了什么。我已多次实现RecyclerView。但是这个项目我不知道我做错了什么，Recyclerview不会显示。请帮助

Answer 1

更改您致电的地方：

 getApplicationContext()

使用：

MainActivity.this

因为你不在内班你可以打电话：

this

Answer 2

编辑：尝试使用this代替getApplicationContext（）;

试试这个。

@Override public VideoAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType){ 
View view = LayoutInflater.from(context).inflate(R.layout.list_item, parent,false); 
return new MyViewHolder(view); 
}

Answer 3

您是否在build.gradle中添加了正确的版本。

试

compile 'com.android.support:recyclerview-v7:25.0.1'

您也可以参考以下简单的Recyclerview代码

https://github.com/thinu/android-recyclerview-simple/

Answer 4

public class Video { private String videoUrl; public Video() { } public Video(String videoUrl) { this.videoUrl = videoUrl; } public String getVideoUrl() { return videoUrl; } public void setVideoUrl(String videoUrl) { this.videoUrl = videoUrl; } }``

在视频课程中，使用getter而不是setter可能会有效。

RecyclerView不会显示任何数据

4 个答案: