java - 使用自定义 ListView 布局中的按钮增加 Int 的值

Question

我最近成功制作了自定义 ListView 布局并从 ListView 填充该数据。
ListView 包含一个“喜欢”按钮和一个存储喜欢数量的 TextView 。但我似乎无法弄清楚如何获取该 int 并在按下按钮时增加它，因为这将在 CustomAdapter 中执行。

数据模型:

public class MessagesListDataModel {
 private String uid;
 private String msg;
 private String likes;
 private String date;
 private Button like;
 private Button reply;


public MessagesListDataModel(String uid, String msg, String date) {
    this.uid = uid;
    this.msg = msg;
    this.date = date;
    this.likes = likes;
}
public MessagesListDataModel(){

}

public String getUid() {
    return uid;
}

public void setUid(String uid) {
    this.uid = uid;
}

public String getMsg() {
    return msg;
}

public void setMsg(String msg) {
    this.msg = msg;
}
public String getLikes() {
    return likes;
}

public void setLikes(String likes) {
    this.likes = likes;
}

public String getDate() {
    return date;
}

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

public Button getLike() {
    return like;
}

public void setLike(Button like) {
    this.like = like;
}
}

适配器:

public class MessagesListAdapter extends ArrayAdapter<MessagesListDataModel> {

private ArrayList<MessagesListDataModel> dataModels;

public MessagesListAdapter(Context context, ArrayList<MessagesListDataModel> dataModels){
    super(context,0, dataModels);
    this.dataModels = dataModels;

}

/*
 * we are overriding the getView method here - this is what defines how each
 * list item will look.
 */
public View getView(int position, View convertView, ViewGroup parent){

    MessagesListDataModel messagesListDataModel = dataModels.get(position);

    // first check to see if the view is null. if so, we have to inflate it.
    // to inflate it basically means to render, or show, the view.
    if (convertView == null) {
        convertView = LayoutInflater.from(getContext()).inflate(R.layout.chat_messages_layout, parent, false);
    }


        TextView uid = (TextView) convertView.findViewById(R.id.textViewUserID);
        TextView message = (TextView) convertView.findViewById(R.id.textViewMessage);
        TextView likes = (TextView) convertView.findViewById(R.id.textViewLikes);
        TextView date = (TextView) convertView.findViewById(R.id.textViewDateTime);
        Button like = (Button) convertView.findViewById(R.id.buttonLike);
        Button reply = (Button) convertView.findViewById(R.id.buttonReply);

        uid.setText(messagesListDataModel.getUid());
        message.setText(messagesListDataModel.getMsg());
        date.setText(messagesListDataModel.getDate());
        likes.setText(messagesListDataModel.getLikes());

        like.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast toast = Toast.makeText(getContext(), "Like button pressed", Toast.LENGTH_SHORT);
                toast.show();
                //Increment the value of the likes textview and reload that textview to display new likes. Limit the likes to only be able to like a post once.

            }
        });

        reply.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast toast = Toast.makeText(getContext(), "reply button pressed", Toast.LENGTH_SHORT);
                toast.show();
                //passing data for the reference in the replies class.



            }
        });

    return convertView;


}
}

在like.SetOnClickListener中，我如何从Firebase数据库中检索存储为“喜欢”的数据，通过添加1来更新int并将其存储回数据库？

这是否可以在适配器中完成，或者是否需要在填充数据的“主要 Activity ”中进行？我不知道该怎么做。

另一个问题是 TextView 不接受 Int，所以我需要在执行此操作时从字符串转换为 int 并返回？

主要 Activity :

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

    //for sending messages to database
    btn_send_msg = (Button) findViewById(R.id.btn_send);
    input_msg = (EditText) findViewById(R.id.msg_Input);

    //Date time
    //DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
    //dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
    //Date date = new Date();
    //String dtSent = ((dateFormat.format(date).toString()));



    //UserData student ID
    FirebaseUser loggedinFirebaseUser = FirebaseAuth.getInstance().getCurrentUser();
    String userId = loggedinFirebaseUser.getUid();

    room_name = getIntent().getExtras().get("room_name").toString();
    setTitle(" Room - " + room_name);


    //stores the reference as a string to be passed onto the userDataReference table
    databaseUrlRef = "users/userData" + "/" + userId;
    userDataRef = FirebaseDatabase.getInstance().getReference(databaseUrlRef + "/SID");
    chatroomsref = FirebaseDatabase.getInstance().getReference("Chatrooms").child(room_name);

    ///////
    final MessagesListAdapter arrayAdapter = new MessagesListAdapter(this,arrayMessages);

    ListViewMessages = (ListView) findViewById(R.id.chatRoomMessagesListview);
    ListViewMessages.setAdapter(arrayAdapter);


    chatroomsref.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            //fetchData();
            //for (DataSnapshot child : dataSnapshot.getChildren()) {
                MessagesListDataModel messagesListDataModel =
                        dataSnapshot.getValue(MessagesListDataModel.class);
                arrayMessages.add(messagesListDataModel);

            arrayAdapter.notifyDataSetChanged();
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });



    /////
    //reference to the database that is within the chatrooms and the room name of the name that was clicked and passed onto this activity.
    root = FirebaseDatabase.getInstance().getReference("Chatrooms/" + room_name);

    userDataRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String Name = dataSnapshot.getValue().toString();
            user_name = Name;
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });


    //https://stackoverflow.com/questions/40891268/how-to-get-firebase-data-into-a-listview
    btn_send_msg.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Date date = new Date();
            DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
            dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
            String dtSent = ((dateFormat.format(date).toString()));

            Map<String, Object> map = new HashMap<String, Object>();
            temp_key = root.push().getKey();
            // temp key is the randomly generated key
            root.updateChildren(map);

            DatabaseReference message_root = root.child(temp_key);
            Map<String, Object> map2 = new HashMap<String, Object>();
            map2.put("uid", user_name);
            map2.put("msg", input_msg.getText().toString());
            map2.put("likes","0");
            map2.put("date",dtSent);

            message_root.updateChildren(map2);
            input_msg.setText("");
        }
    });

}
}

我主要寻找的是如何访问数据库中的结构(Chatrooms/RoomName/UNIQUE_ID/likes)，并更新它。其中Unique id 是实际的唯一id。

FATAL EXCEPTION: main Process: com.brunelcs.group13.anyquestions, PID: 8808 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference at com.brunelcs.group13.anyquestions.ChatRoom$1.onButtonClick(ChatRoom.java:87) at com.brunelcs.group13.anyquestions.MessagesListAdapter$1.onClick(MessagesListAdapter.java:81) at android.view.View.performClick(View.java:6256) at android.view.View$PerformClick.run(View.java:24697) at android.os.Handler.handleCallback(Handler.java:789) at android.os.Handler.dispatchMessage(Handler.java:98) at android.os.Looper.loop(Looper.java:164) at android.app.ActivityThread.main(ActivityThread.java:6541) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Toast toast = Toast.makeText(getApplicationContext(), getPostKey.toString(), Toast.LENGTH_SHORT);
            toast.show();

我放在 getPostKey 之后，

另一个:

if (btnClickListener != null)
                    btnClickListener.onButtonClick((Integer) view.getTag());}

此外，arrayAdapter 也必须更改为此，因为它出现错误:

 final MessagesListAdapter arrayAdapter = new  MessagesListAdapter(this, arrayMessages, new MessagesListAdapter.ButtonClickListener() {}

这就是我将数据发布到 firebase 的方式:

btn_send_msg.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Date date = new Date();
            DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
            dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
            String dtSent = ((dateFormat.format(date).toString()));

            Map<String, Object> map = new HashMap<String, Object>();
            temp_key = root.push().getKey();
            // temp key is the randomly generated key
            root.updateChildren(map);

            DatabaseReference message_root = root.child(temp_key);
            Map<String, Object> map2 = new HashMap<String, Object>();
            map2.put("uid", user_name);
            map2.put("msg", input_msg.getText().toString());
            map2.put("likes","0");
            map2.put("date",dtSent);

            message_root.updateChildren(map2);
            input_msg.setText("");
        }
    });

Answer 1

正如您从我在评论中发布的答案中看到的，您可以在 Adapter 类中使用一个 void 方法和 int 创建一个接口(interface)作为参数，例如:

public interface ButtonClickListener {
   public abstract void onButtonClick(int position);
}

然后在适配器类的构造函数中使用它，以便您可以在 Activity 中覆盖它并预制 ButtonClick。例如:

private ButtonClickListener btnClickListener = null;
public MessagesListAdapter(Context context, ArrayList<MessagesListDataModel> dataModels, ButtonClickListener btnClickListener){
super(context,0, dataModels);
this.dataModels = dataModels;
this.btnClickListener = btnClickListener;
}

之后，在 like 按钮上的 Adapter 类 setTag 和其上的 setOnclickListener 并获取标签。例如:

likes.setTag(position);
likes.setOnClickListener(new View.OnClickListener{
   @Override
    public void onClick(View v) {

    if(btnClickListener != null)
        btnClickListener.onButtonClick((Integer) v.getTag());                
   }
});

完成此操作后，您将能够在 Activity 中的适配器创建中实现点击监听器，然后在内部使用 position 获取 post 的 key 并使用该 key 键，检索您对特定帖子的点赞数，增加并再次设置该值。在模型类中创建一个新的 getter 和 setter 来存储 key，例如:

private String postKey;

public String getPostKey() {
    return postKey;
}

public void setPostKey(String postKey) {
    this.postKey = postKey;
}

您需要将 key 存储在 sePostKey 中，以便可以从 getPostKey 获取 key 。然后您可以轻松地从 MessagesListDataModel 获取它:

final MessagesListAdapter arrayAdapter = new  MessagesListAdapter(this,arrayMessages, new ButtonClickListener(){
 @Override
  public void onButtonClick(int position) {
   String getPostKey = arrayMessages.get(position).getPostKey();
  //Now you have a key to run another query to get data from specific post and with that number of likes as well
   }
});

可能可以简化流程或使用其他更好的方法，但这只是您如何实现您想要的目标的一个想法。我没有测试这段代码，我希望它能起作用。