java - Android studio RecyclerView 按日期分组？

Question

我正在开发一个聊天应用程序。 但我无法按日期对邮件进行分组。我是 Android studio 和 java 的新手。 谁能告诉我该怎么做？

我的代码:

MessageActivity.java

public class MessageActivity extends AppCompatActivity {

    CircleImageView profile_image;
    TextView username, status;

    FirebaseUser fuser;
    DatabaseReference reference;

    ImageButton btn_send;
    EditText text_send;

    MessageAdapter messageAdapter;
    List<Chat> mchat;

    RecyclerView recyclerView;

    Intent intent;

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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });

        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getApplicationContext());
        linearLayoutManager.setStackFromEnd(true);
        recyclerView.setLayoutManager(linearLayoutManager);

        profile_image = findViewById(R.id.profile_image);
        username = findViewById(R.id.username);
        status = findViewById(R.id.status);
        btn_send = findViewById(R.id.btn_send);
        text_send = findViewById(R.id.text_send);

        intent = getIntent();
        final String userid = intent.getStringExtra("userid");
        fuser = FirebaseAuth.getInstance().getCurrentUser();

        btn_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String msg = text_send.getText().toString();
                if (!msg.equals("")) {
                    sendMessage(fuser.getUid(), userid, msg);
                } else {
                    text_send.setError(getResources().getText(R.string.you_cant_send_empty_message));
                }
                text_send.setText("");
            }
        });

        reference = FirebaseDatabase.getInstance().getReference("Users").child(userid);
        reference.keepSynced(true);
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                final User user = dataSnapshot.getValue(User.class);
                final String fullNumber;
                boolean showProfilePhoto;
                boolean showLastSeen;
                if (ContextCompat.checkSelfPermission(MessageActivity.this,
                        Manifest.permission.READ_CONTACTS) == PackageManager.PERMISSION_GRANTED) {
                    if (contactExists(MessageActivity.this, user.getNumber())){
                        username.setText(getContactName(user.getNumber() ,MessageActivity.this));
                    }else{
                        fullNumber = ""+user.getArea_code()+""+user.getNumber();
                        username.setText(fullNumber);
                    }
                } else {
                    fullNumber = ""+user.getArea_code()+""+user.getNumber();
                    username.setText(fullNumber);
                }
                if (user.getDisplayProfilePhoto().equals("everyone")) {
                    showProfilePhoto = true;
                } else if (user.getDisplayProfilePhoto().equals("contacts")){
                    Everywhere everywhere = new Everywhere();
                    showProfilePhoto = everywhere.isContact(user.getId());
                } else {
                    showProfilePhoto = false;
                }
                if (showProfilePhoto) {
                    if (user.getImageURL().equals("default")){
                        profile_image.setImageResource(R.drawable.profile_image);
                    } else {
                        Picasso.get().load(user.getImageURL()).networkPolicy(NetworkPolicy.OFFLINE).into(profile_image, new Callback() {
                            @Override
                            public void onSuccess() {

                            }

                            @Override
                            public void onError(Exception e) {
                                Picasso.get().load(user.getImageURL()).into(profile_image);
                            }
                        });
                    }
                }else {
                    profile_image.setImageResource(R.drawable.profile_image);
                }
                if (user.getDisplayLastSeen().equals("everyone")) {
                    showLastSeen = true;
                } else if (user.getDisplayLastSeen().equals("contacts")){
                    Everywhere everywhere = new Everywhere();
                    showLastSeen = everywhere.isContact(user.getId());
                } else {
                    showLastSeen = false;
                }

                if (showLastSeen) {
                    if (user.getStatus().equals("online")){
                        status.setText(getResources().getString(R.string.online));
                    } else {
                        String lastSeenTime = DateFormat.format("HH:mm", user.getLastSeen()).toString();
                        String lastSeenDate = DateFormat.format("dd/MM/yyyy HH:mm", user.getLastSeen()).toString();
                        String lastSeenDayMounthYear = DateFormat.format("dd/MM/yyyy", user.getLastSeen()).toString();
                        long today = System.currentTimeMillis();
                        String todayDayMounthYear = DateFormat.format("dd/MM/yyyy", today).toString();
                        if (lastSeenDayMounthYear.equals(todayDayMounthYear)) {
                            status.setText(getResources().getString(R.string.last_seen)+" "+getResources().getString(R.string.today_lower)+" "+lastSeenTime);
                        } else {
                            status.setText(getResources().getString(R.string.last_seen)+" "+lastSeenDate);
                        }
                    }
                }

                readMessages(fuser.getUid(), userid, user.getImageURL());
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

    private boolean contactExists(Context _mContext, String number) {
        if (number != null) {
            Uri lookupUri = Uri.withAppendedPath(ContactsContract.PhoneLookup.CONTENT_FILTER_URI, Uri.encode(number));
            String[] mPhoneNumberProjection = { ContactsContract.PhoneLookup._ID, ContactsContract.PhoneLookup.NUMBER, ContactsContract.PhoneLookup.DISPLAY_NAME };
            Cursor cur = _mContext.getContentResolver().query(lookupUri, mPhoneNumberProjection, null, null, null);
            try {
                assert cur != null;
                if (cur.moveToFirst()) {
                    return true;
                }
            } finally {
                if (cur != null)
                    cur.close();
            }
            return false;
        } else {
            return false;
        }
    }

    public String getContactName(final String phoneNumber, Context context)
    {
        Uri uri=Uri.withAppendedPath(ContactsContract.PhoneLookup.CONTENT_FILTER_URI,Uri.encode(phoneNumber));

        String[] projection = new String[]{ContactsContract.PhoneLookup.DISPLAY_NAME};

        String contactName="";
        Cursor cursor=context.getContentResolver().query(uri,projection,null,null,null);

        if (cursor != null) {
            if(cursor.moveToFirst()) {
                contactName=cursor.getString(0);
            }
            cursor.close();
        }

        return contactName;
    }

    private void sendMessage(String sender, String receiver, String message) {

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
        reference.keepSynced(true);
        HashMap<String, Object> hashMap = new HashMap<>();
        hashMap.put("sender", sender);
        hashMap.put("receiver", receiver);
        hashMap.put("message", message);
        hashMap.put("date", System.currentTimeMillis());

        reference.child("Chats").push().setValue(hashMap, new DatabaseReference.CompletionListener() {
            @Override
            public void onComplete(@Nullable DatabaseError databaseError, @NonNull DatabaseReference databaseReference) {
                if (databaseError == null){
                    databaseReference.keepSynced(true);
                    HashMap<String, Object> successMap = new HashMap<>();
                    successMap.put("sended", 1);
                    databaseReference.updateChildren(successMap);
                }
            }
        });

    }

    private void readMessages(final String myid, final String userid, final String imageurl){
        mchat = new ArrayList<>();
        reference = FirebaseDatabase.getInstance().getReference("Chats");
        reference.keepSynced(true);
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                mchat.clear();
                for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                    Chat chat = snapshot.getValue(Chat.class);
                    if (chat.getReceiver().equals(myid) && chat.getSender().equals(userid) ||
                            chat.getReceiver().equals(userid) && chat.getSender().equals(myid)){
                        mchat.add(chat);
                    }

                    messageAdapter = new MessageAdapter(MessageActivity.this, mchat, imageurl);
                    recyclerView.setAdapter(messageAdapter);
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        Everywhere everywhere = new Everywhere();
        everywhere.status("online");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Everywhere everywhere = new Everywhere();
        everywhere.status("offline");
    }
}

MessageAdapter.java

public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.ViewHolder> {

    public static  final int MSG_TYPE_LEFT = 0;
    public static  final int MSG_TYPE_RIGHT = 1;

    private Context mContext;
    private List<Chat> mChat;
    private String imageurl;

    FirebaseUser fuser;

    public MessageAdapter(Context mContext, List<Chat> mChat, String imageurl){
        this.mChat = mChat;
        this.mContext = mContext;
        this.imageurl = imageurl;
    }

    @NonNull
    @Override
    public MessageAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        if (viewType == MSG_TYPE_RIGHT) {
            View view = LayoutInflater.from(mContext).inflate(R.layout.chat_item_right, parent, false);
            return new MessageAdapter.ViewHolder(view);
        } else {
            View view = LayoutInflater.from(mContext).inflate(R.layout.chat_item_left, parent, false);
            return new MessageAdapter.ViewHolder(view);
        }
    }

    @Override
    public void onBindViewHolder(@NonNull final MessageAdapter.ViewHolder holder, int position) {

        Chat chat = mChat.get(position);

        holder.show_message.setText(chat.getMessage());
        String message_date = DateFormat.format("HH:mm", chat.getDate()).toString();
        holder.date.setText(message_date);

        if (imageurl.equals("default")) {
            holder.profile_image.setImageResource(R.drawable.profile_image);
        } else {
            Picasso.get().load(imageurl).networkPolicy(NetworkPolicy.OFFLINE).into(holder.profile_image, new Callback() {
                @Override
                public void onSuccess() {

                }

                @Override
                public void onError(Exception e) {
                    Picasso.get().load(imageurl).into(holder.profile_image);
                }
            });
        }

    }

    @Override
    public int getItemCount() {
        return mChat.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        public TextView show_message, date;
        public ImageView profile_image;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);

            show_message = itemView.findViewById(R.id.show_message);
            date = itemView.findViewById(R.id.date);
            profile_image = itemView.findViewById(R.id.profile_image);

        }
    }

    @Override
    public int getItemViewType(int position) {
        fuser = FirebaseAuth.getInstance().getCurrentUser();
        if (mChat.get(position).getSender().equals(fuser.getUid())) {
            return MSG_TYPE_RIGHT;
        } else {
            return MSG_TYPE_LEFT;
        }
    }
}

聊天模型(获取聊天数据)

public class Chat {

    private String sender;
    private String receiver;
    private String message;
    private long date;

    public Chat(String sender, String receiver, String message, long date) {
        this.sender = sender;
        this.receiver = receiver;
        this.message = message;
        this.date = date;
    }

    public Chat() {
    }

    public String getSender() {
        return sender;
    }

    public void setSender(String sender) {
        this.sender = sender;
    }

    public String getReceiver() {
        return receiver;
    }

    public void setReceiver(String receiver) {
        this.receiver = receiver;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public long getDate() {
        return date;
    }

    public void setDate(long date) {
        this.date = date;
    }
}

用户模型(获取用户数据)

public class User {

    private String id;
    private String username;
    private String imageURL;
    private String number;
    private String area_code;
    private String about;
    private String status;
    private long lastSeen;
    private String displayLastSeen;
    private String displayProfilePhoto;
    private String displayAbout;
    private String displayStory;

    public User(String id, String username, String imageURL, String number, String area_code, String about, String status, long lastSeen, String displayLastSeen, String displayProfilePhoto, String displayAbout, String displayStory) {
        this.id = id;
        this.username = username;
        this.imageURL = imageURL;
        this.number = number;
        this.area_code = area_code;
        this.about = about;
        this.status = status;
        this.lastSeen = lastSeen;
        this.displayLastSeen = displayLastSeen;
        this.displayProfilePhoto = displayProfilePhoto;
        this.displayAbout = displayAbout;
        this.displayStory = displayStory;
    }

    public User() {
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getImageURL() {
        return imageURL;
    }

    public void setImageURL(String imageURL) {
        this.imageURL = imageURL;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    public String getArea_code() {
        return area_code;
    }

    public void setArea_code(String area_code) {
        this.area_code = area_code;
    }

    public String getAbout() {
        return about;
    }

    public void setAbout(String about) {
        this.about = about;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public long getLastSeen() {
        return lastSeen;
    }

    public void setLastSeen(long lastSeen) {
        this.lastSeen = lastSeen;
    }

    public String getDisplayLastSeen() {
        return displayLastSeen;
    }

    public void setDisplayLastSeen(String displayLastSeen) {
        this.displayLastSeen = displayLastSeen;
    }

    public String getDisplayProfilePhoto() {
        return displayProfilePhoto;
    }

    public void setDisplayProfilePhoto(String displayProfilePhoto) {
        this.displayProfilePhoto = displayProfilePhoto;
    }

    public String getDisplayAbout() {
        return displayAbout;
    }

    public void setDisplayAbout(String displayAbout) {
        this.displayAbout = displayAbout;
    }

    public String getDisplayStory() {
        return displayStory;
    }

    public void setDisplayStory(String displayStory) {
        this.displayStory = displayStory;
    }
}

chat_item_date.xml(显示日期，但我无法使用它。)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="5dp">

    <TextView
        android:id="@+id/txtGroupDate"
        android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:text="DATE"
    android:padding="5dp"
    android:background="@drawable/rounded_corner"
    android:textColor="#707c83"/>

</RelativeLayout>

chat_item_left.xml(与chat_item_right.xml相同)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="8dp">
<RelativeLayout
    android:layout_width="300dp"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    // android:layout_alignParentEnd="true"
    // in chat_item_right.xml
    >

    <de.hdodenhof.circleimageview.CircleImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/profile_image"
        android:visibility="gone"/>

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:background="@drawable/background_left"
        // android:background="@drawable/background_right"
        // in chat_item_right.xml
        android:layout_alignParentStart="true"
        // android:layout_alignParentEnd="true"
        // in chat_item_right.xml
        >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="hello"
            android:id="@+id/show_message"
            android:maxWidth="255dp"
            android:textSize="18sp"
            android:padding="8dp"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toEndOf="@id/show_message"
            android:layout_alignBottom="@id/show_message"
            android:layout_marginBottom="5dp"
            android:text="00:00"
            android:id="@+id/date"
            android:textSize="12sp"
            />
    </RelativeLayout>

</RelativeLayout>

Answer 1

因此，RecyclerView 的分组是由列表的排序方式决定的。您需要根据日期为列表编写一个排序器。

如果您需要帮助，请尝试此链接:Sort objects in ArrayList by date?